Generac Power Systems Guardian 04389-1 Installation instructions

GENERAC
POWER SYSTEMS, INC.
R
R
Installation and
Owner’s Manual
Air-cooled, Prepackaged
Automatic Standby Generators
Models:
04389-1 (6 kW NG, 7 kW LP)
04456-1 (12 kW NG, 12 kW LP)
04390-1 (13 kW NG, 15 kW LP)
DEADLY EXHAUST FUMES. OUTDOOR INSTALLATION ONLY!!
DANGER
Not intended for use as Primary Power in place of utility or in
life-support applications.
!!

Generac®Power Systems, Inc.
INTRODUCTION
Thank you for purchasing this model of the Guardian
product line by Generac Power Systems Inc. This
model is a compact, high performance, air-cooled,
engine-driven generator designed to automatically
supply electrical power to operate critical loads dur-
ing a utility power failure.
This unit is factory installed in an all-weather, metal enclo-
sure that is intended exclusively for outdoor installation.
This generator will operate using either vapor withdrawn
liquid propane (LP) or natural gas (NG).
READ THIS MANUAL THOROUGHLY
If any portion of this manual is not understood, contact
Generac or the nearest Generac/Guardian Authorized
Dealer for starting, operating and servicing procedures.
Throughout this publication, and on tags and
decals affixed to the generator, DANGER, WARNING,
CAUTION and NOTE blocks are used to alert per-
sonnel to special instructions about a particular
operation that may be hazardous if performed incor-
rectly or carelessly. Observe them carefully. Their def-
initions are as follows:
After this heading, read instructions that, if not
strictly complied with, will result in serious person-
al injury, including death, in addition to property
damage.
After this heading, read instructions that, if not
strictly complied with, may result in serious person-
al injury or property damage.
After this heading, read instructions that, if not
strictly complied with, could result in damage to
equipment and/or property.
NOTE:
After this heading, read explanatory statements
that require special emphasis.
These safety warnings cannot eliminate the hazards
that they indicate. Common sense and strict compli-
ance with the special instructions while performing the
service are essential to preventing accidents.
Four commonly used safety symbols accompany the
DANGER, WARNING and CAUTION blocks. The type
of information each indicates follows:
This symbol points out important safety informa-
tion that, if not followed, could endanger personal
safety and/or property of you and others.
This symbol points out potential explosion hazard.
This symbol points out potential fire hazard.
This symbol points out potential electrical shock
hazard.
The operator is responsible for proper and safe use
of the equipment. Genrac strongly recommends that
the operator read this Owner's Manual and thor-
oughly understand all instructions before using this
equipment. Generac also strongly recommends
instructing other users to properly start and operate
the unit. This prepares them if they need to operate
the equipment in an emergency.
CONTENTS
This manual contains pertinent owner’s information,
including warranty, electrical diagrams, exploded
views and lists of repair parts, for three different
Guardian models:
• 04389-1 – 6 kW NG, 7 kW LP, single-cylinder GH-
410 Engine
• 04456-1 – 12 kW NG, 12 kW LP, V-twin GT-990
Engine
• 04390-1 – 13 kW NG, 15 kW LP, V-twin GT-990
Engine
OPERATION AND MAINTENANCE
It is the operator's responsibility to perform all safe-
ty checks, to make sure that all maintenance for safe
operation is performed promptly, and to have the
equipment checked periodically by a
Generac/Guardian Authorized Dealer. Normal main-
tenance service and replacement of parts are the
responsibility of the owner/operator and, as such, are
not considered defects in materials or workmanship
within the terms of the warranty. Individual operating
habits and usage contribute to the need for mainte-
nance service.
Proper maintenance and care of the generator
ensures a minimum number of problems and keep
operating expenses at a minimum. See a
Generac/Guardian Authorized Dealer for service aids
and accessories.
HOW TO OBTAIN SERVICE
When the generator requires servicing or repairs,
simply contact a Generac/Guardian Authorized
Dealer for assistance. Service technicians are factory-
trained and are capable of handling all service needs.
When contacting a Generac/Guardian Authorized
Dealer or the factory about parts and service, always
supply the complete model number and serial number
of your unit as given on its data decal, which is locat-
ed on the generator. See Figure 1.1 or Figure 1.2 in
Section 1.6 for decal location.
Model No. ____________ Serial No. ______________
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DANGER
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AUTHORIZED
DEALER LOCATION
To locate the nearest GENERAC/GUARDIAN
AUTHORIZED DEALER, please call this number:
1-800-333-1322
DEALER LOCATION INFORMATION
CAN BE OBTAINED AT THIS NUMBER.

Table of Contents
Guardian Air-cooled 7 kW, 12 kW and 15 kW Generators
Generac®Power Systems, Inc. 1
Introduction ........................Inside Front Cover
Read This Manual Thoroughly ........................IFC
Contents ..........................................................IFC
Operation and Maintenance ............................IFC
How to Obtain Service ....................................IFC
Authorized Dealer Locator Number ....................IFC
Safety Rules ........................................................2
Standards Index ..................................................3
Section 1 – General Information ..................4
1.1 Unpacking/Inspection ....................................4
1.2 Protection Systems ........................................4
1.3 System Set LED ............................................4
1.4 Your Generator ..............................................5
1.5 Specifications ................................................6
1.5.1 Generator ..........................................6
1.5.2 Engine ................................................6
1.6 Fuel Requirements and Recommendations....7
1.7 Fuel Consumption ........................................7
1.8 Reconfiguring the Fuel System ......................7
1.8.1 7 kW, 410cc Engine ............................7
1.8.2 12 kW and 15 kW, 990cc Engine ........7
1.9 Location ........................................................8
1.9.1 Generator ..........................................8
1.9.2 Transfer Switch ..................................8
1.10 Battery Installation ........................................9
1.11 The Battery....................................................9
Section 2 – Post Installation Start-up
and Adjustments ......................10
2.1 Before Initial Startup ..................................10
2.2 Check Transfer Switch Operation................10
2.3 Electrical Checks ........................................10
2.4 Generator Tests Under Load ......................11
2.5 Checking Automatic Operation ....................11
2.6 Adjusting the Regulator (Natural Gas Only) ..12
2.7 Engine Governor Adjustment ......................12
2.7.1 7 kW Units ......................................12
2.7.2 12 kW and 15 kW Units ..................13
2.7.3 Additional Corrosion Protection ......13
2.8 Voltage Regulator Adjustment ......................13
Section 3 – Operation ....................................14
3.1 Break-in Procedure......................................14
3.2 Using the Auto/Off/Manual Switch ..............14
3.2.1 “Auto” Position ..................................14
3.2.2 “Off” Position ....................................14
3.2.3 “Manual” Position ............................14
3.3 Automatic Transfer Operation ....................14
3.4 Sequence of Automatic Operation................15
3.5 Manual Transfer Operation ........................15
3.5.1 Transfer to Generator
Power Source......................................15
3.5.2 Transfer Back to Utility
Power Source......................................16
3.6 Setting the Exercise Timer ..........................16
3.7 Protection Systems ......................................16
3.7.1 Low Oil Pressure Switch ..................16
3.7.2 High Temperature Switch ................16
3.7.3 Overcrank ........................................16
3.7.4 Overspeed ........................................17
Section 4 – Maintenance ..............................17
4.1 Fuse ............................................................17
4.2 Checking the Engine Oil Level ....................17
4.3 Changing the Engine Oil ..............................18
4.3.1 Engine Oil Recommendations ..........18
4.3.2 Oil Change Procedure ......................18
4.4 Changing the Oil Filter ................................18
4.5 Changing the Engine Air Cleaner ................18
4.5.1 7 kW, 12 kW and 15 kW
Generators........................................18
4.6 Spark Plug(s) ..............................................19
4.7 Battery Maintenance ....................................19
4.8 Adjusting GH-410/GT-990 Valve Clearance ..20
4.9 Cooling System............................................20
4.10 Attention After Submersion ........................21
4.11 Corrosion Protection ..................................21
4.12 Out of Service Procedure ............................21
4.12.1 Removal From Service ......................21
4.12.2 Return to Service..............................21
4.13 Service Schedule ........................................22
Section 5 – Troubleshooting ........................23
5.1 Troubleshooting Guide ................................23
Section 6 – Electrical Data ............................24
Section 7 – Exploded Views and
Parts Lists....................................32
Section 8 – Mounting Dimensions..............53
Section 9 – Notes ............................................54
Section 10 – Warranty....................................56

2 Generac®Power Systems, Inc.
Study these SAFETY RULES carefully before
installing, operating or servicing this equipment.
Become familiar with this Owner’s Manual and with
the unit. The generator can operate safely, efficiently
and reliably only if it is properly installed, operated
and maintained. Many accidents are caused by failing
to follow simple and fundamental rules or precau-
tions.
Generac cannot possibly anticipate every possible
circumstance that might involve a hazard. The warn-
ings in this manual, and on tags and decals
affixed to the unit are, therefore, not all-inclusive. If
using a procedure, work method or operating tech-
nique Generac does not specifically recommend, sat-
isfy yourself that it is safe for others. Also make sure
the procedure, work method or operating technique
chosen does not render the generator unsafe.
Despite the safe design of this generator,
operating this equipment imprudently, neglecting
its maintenance or being careless can cause
possible injury or death. Permit only responsible
and capable persons to operate or maintain this
equipment.
Potentially lethal voltages are generated by
these machines. Ensure all steps are taken to
render the machine safe before attempting to
work on the generator.
Parts of the generator are rotating and/or hot
during operation. Exercise care near running
generators.
GENERAL HAZARDS
• For safety reasons, Generac recommends that the
installation, initial start-up and maintenance of
this equipment is carried out by an Authorized
Generac/Guardian Dealer.
• The engine exhaust fumes contain carbon monox-
ide, which can be DEADLY. This dangerous gas, if
breathed in sufficient concentrations, can cause
unconsciousness or even death. This exhaust sys-
tem must be installed properly, in strict compli-
ance with applicable codes and standards.
Following installation, do nothing that might ren-
der the system unsafe or in noncompliance with
such codes and standards.
• Keep hands, feet, clothing, etc., away from drive
belts, fans, and other moving or hot parts. Never
remove any drive belt or fan guard while the unit is
operating.
• Adequate, unobstructed flow of cooling and venti-
lating air is critical to correct generator operation.
Do not alter the installation or permit even partial
blockage of ventilation provisions, as this can seri-
ously affect safe operation of the generator. The
generator MUST be installed outdoors.
• When working on this equipment, remain alert at
all times. Never work on the equipment when
physically or mentally fatigued.
• Inspect the generator regularly, and contact the
nearest Generac/Guardian Authorized Dealer for
parts needing repair or replacement.
• Before performing any maintenance on the genera-
tor, disconnect its battery cables to prevent acci-
dental start up. Disconnect the cable from the bat-
tery post indicated by a NEGATIVE, NEG or (–)
first. Reconnect that cable last.
• Never use the generator or any of its parts as a
step. Stepping on the unit can stress and break
parts, and may result in dangerous operating con-
ditions from leaking exhaust gases, fuel leakage,
oil leakage, etc.
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DANGER
IMPORTANT SAFETY INSTRUCTIONS
Guardian Air-cooled 7 kW, 12 kW and 15 kW Generators
SAVE THESE INSTRUCTIONS – The manufacturer suggests that these rules for safe
operation be copied and posted near the unit’s installation site. Safety should be stressed to
all operators and potential operators of this equipment.
!
!
The engine exhaust from this product
contains chemicals known to the state
of California to cause cancer, birth
defects or other reproductive harm.
WARNING:
!!
This product contains or emits chemicals
known to the state of California to cause
cancer, birth defects or other reproductive harm.
WARNING:
!!

Generac®Power Systems, Inc. 3
ELECTRICAL HAZARDS
• All generators covered by this manual produce
dangerous electrical voltages and can cause fatal
electrical shock. Utility power delivers extremely
high and dangerous voltages to the transfer switch
as does the standby generator when it is in opera-
tion. Avoid contact with bare wires, terminals, con-
nections, etc., while the unit is running. Ensure all
appropriate covers, guards and barriers are in
place before operating the generator. If work must
be done around an operating unit, stand on an
insulated, dry surface to reduce shock hazard.
• Do not handle any kind of electrical device while
standing in water, while barefoot, or while hands
or feet are wet. DANGEROUS ELECTRICAL
SHOCK MAY RESULT.
• The National Electrical Code (NEC) requires the
frame and external electrically conductive parts of
the generator to be connected to an approved earth
ground. Local electrical codes also may require
proper grounding of the generator electrical system.
• After installing this home standby electrical sys-
tem, the generator may crank and start at any time
without warning. When this occurs, load circuits
are transferred to the STANDBY (generator) power
source. To prevent possible injury if such a start
and transfer occur, always set the generator’s
Auto/Off/Manual switch to its OFF position before
working on equipment and remove the 5A and 15A
fuses from the generator control panel.
• In case of accident caused by electric shock, imme-
diately shut down the source of electrical power. If
this is not possible, attempt to free the victim from
the live conductor. AVOID DIRECT CONTACT WITH
THE VICTIM. Use a nonconducting implement,
such as a dry rope or board, to free the victim from
the live conductor. If the victim is unconscious,
apply first aid and get immediate medical help.
• Never wear jewelry when working on this equip-
ment. Jewelry can conduct electricity resulting in
electric shock, or may get caught in moving com-
ponents causing injury.
FIRE HAZARDS
• For fire safety, the generator must be installed and
maintained properly. Installation always must
comply with applicable codes, standards, laws and
regulations. Adhere strictly to local, state and
national electrical and building codes. Comply
with regulations the Occupational Safety and
Health Administration (OSHA) has established.
Also, ensure that the generator is installed in
accordance with the manufacturer’s instructions
and recommendations. Following proper installa-
tion, do nothing that might alter a safe installation
and render the unit in noncompliance with the
aforementioned codes, standards, laws and regu-
lations.
• Keep a fire extinguisher near the generator at all
times. Extinguishers rated “ABC” by the National
Fire Protection Association are appropriate for use
on the standby electric system. Keep the extin-
guisher properly charged and be familiar with its
use. Consult the local fire department with any
questions pertaining to fire extinguishers.
EXPLOSION HAZARDS
• Do not smoke around the generator. Wipe up any
fuel or oil spills immediately. Ensure that no com-
bustible materials are left in the generator com-
partment, or on or near the generator, as FIRE or
EXPLOSION may result. Keep the area surround-
ing the generator clean and free from debris.
• Gaseous fluids such as natural gas and liquid
propane (LP) gas are extremely EXPLOSIVE.
Install the fuel supply system according to applica-
ble fuel-gas codes. Before placing the home stand-
by electric system into service, fuel system lines
must be properly purged and leak tested according
to applicable code. After installation, inspect the
fuel system periodically for leaks. No leakage is
permitted.
STANDARDS INDEX
In the absence of pertinent standards, codes, regula-
tions and laws, the published information listed
below may be used as installation guide for this
equipment.
1. NFPA No. 37, STATIONARY COMBUSTION
ENGINES AND GAS TURBINES, available from
the National Fire Protection Association, 470
Atlantic Avenue, Boston, MA 02210.
2. NFPA No. 76A, ESSENTIAL ELECTRICAL SYS-
TEMS FOR HEALTH CARE FACILITIES, avail-
able same as Item 1.
3. NFPA No. 54, NATIONAL FUEL GAS CODE,
available same as Item 1.
4. NFPA No. 58, AMERICAN NATIONAL STANDARD
FOR STORAGE AND HANDLING OF LIQUEFIED
PETROLEUM GAS, available same as Item 1.
5. NFPA No. 70, NFPA HANDBOOK OF NATIONAL
ELECTRIC CODE, available same as Item 1.
6. Article X, NATIONAL BUILDING CODE, available
from the American Insurance Association, 85
John Street, New York, N.Y. 10038.
7. AGRICULTURAL WIRING HANDBOOK, available
from the Food and Energy Council, 909
University Avenue, Columbia, MO 65201.
8. ASAE EP-3634, INSTALLATION AND MAINTE-
NANCE OF FARM STANDBY ELECTRICAL SYS-
TEMS, available from the American Society of
Agricultural Engineers, 2950 Niles Road, St.
Joseph, MI 49085.
9. NFPA No. 30, FLAMMABLE AND COMBUSTIBLE
LIQUIDS CODE, available same as Item 1.
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IMPORTANT SAFETY INSTRUCTIONS
Guardian Air-cooled 7 kW, 12 kW and 15 kW Generators

Only qualified electricians or contractors should
attempt such installations, which must comply
strictly with applicable codes, standards and
regulations.
1.1 UNPACKING/INSPECTION
After unpacking, carefully inspect the contents
for damage.
• This standby generator set has been factory sup-
plied with a weather protective enclosure that is
intended for outdoor installation only.
• This standby generator set is packaged with an
automatic transfer switch with built in load center.
The combination transfer switch and load center is
pre-wired with a two foot and 30 foot conduit.
Circuit breakers for emergency circuit connections
are included.
• This UL listed, 2-pole switch is rated at 100 AC
amperes at 250 volts maximum. This transfer
switch is for indoor use only.
If this generator is used to power electrical load
circuits normally powered by a utility power
source, it is required by code to install a trans-
fer switch. The transfer switch must effectively
isolate the electrical system from the utility dis-
tribution system when the generator is operat-
ing (NEC 700, 701 & 702). Failure to isolate an
electrical system by such means will result in
damage to the generator and also may result in
injury or death to utility power workers due to
backfeed of electrical energy.
If any loss or damage is noted at time of delivery, have
the person(s) making the delivery note all damage on
the freight bill or affix their signature under the con-
signor's memo of loss or damage.
If a loss or damage is noted after delivery, separate
the damaged materials and contact the carrier for
claim procedures.
“Concealed damage” is understood to mean damage
to the contents of a package that is not in evidence at
the time of delivery, but is discovered later.
1.2 PROTECTION SYSTEMS
Unlike an automobile engine, the generator may have
to run for long periods of time with no operator pres-
ent to monitor engine conditions. For that reason, the
engine is equipped with the following systems that
protect it against potentially damaging conditions:
1. Low Oil Pressure Sensor 3. Overcrank
2. High Temperature Sensor 4. Overspeed
There are LED readouts on the control panel to noti-
fy you that one of these faults has occurred. There is
also a “System Set” LED that is lit when all of the con-
ditions describe in Section 1.3 are true.
1.3 SYSTEM SET LED
The “System Set” LED is lit when all of the following
conditions are true:
1. The Auto/Off/Manual switch is set to the AUTO
position.
2. The utility voltage being supplied to the unit is
being sensed by the PCB. If the utility sense volt-
age is not connected to the unit or if it is below
168 volts AC, then the system set light will flash
rapidly. This indicates that if the Auto/Off/Manual
switch is placed in the Auto position , the genera-
tor will start.
3. The “Not In Auto” dip switch is set to the OFF
position on the control board.
4. No alarms are present, for example, low oil pres-
sure, high temperature, etc.
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DANGER
Section 1 — General Information
Guardian Air-cooled 7 kW, 12 kW and 15 kW Generators
4 Generac®Power Systems, Inc.

Section 1 — General Information
Guardian Air-cooled 7 kW, 12 kW and 15 kW Generators
Generac®Power Systems, Inc. 5
1.4 YOUR GENERATOR
Control Panel
Battery Compartment
Fuel Regulator
Air Filter
Exhaust
Enclosure
Oil Filter
Data Decal
Control
Panel
Air Filter
Exhaust
Enclosure
Battery Compartment
Fuel Regulator
Oil Filter
Oil Dipstick
Data
Decal
Figure 1.2 – 12 kW and 15 kW, V-twin GT-990 Engine
Figure 1.1 – 7 kW, Single Cylinder GH-410 Engine

6 Generac®Power Systems, Inc.
Section 1 — General Information
Guardian Air-cooled 7 kW, 12 kW and 15 kW Generators
1.5 SPECIFICATIONS
1.5.1 GENERATOR
Model 04389-1 Model 04456-1 Model 04390-1
Rated Max. Continuous Power Capacity (Watts*) 6,000 NG/7,000 LP 12,000 NG/12,000 LP 13,000 NG/15,000 LP†
Rated Voltage 120/240 120/240 120/240
Rated Max. Continuous Load Current (Amps)
120 Volts** 50.0 NG/58.3 LP 100.0 NG/100.0 LP 108.3 NG/125.0 LP
240 Volts 25.0 NG/29.2 LP 50.0 NG/50.0 LP 54.2 NG/62.5 LP
Main Line Circuit Breaker 30 Amp 50 Amp 60 Amp/70 Amp†
Phase 1 1 1
Number of Rotor Poles 2 2 2
Rated AC Frequency 60 Hz 60 Hz 60 Hz
Power Factor 1 1 1
Recommended Air Filter Generac Part # C8127 Generac Part # C8127 Generac Part # C8127
Battery Requirement Group 26/26R Group 26/26R Group 26/26R
12 Volts and 12 Volts and 12 Volts and
350 Cold-cranking 550 Cold-cranking 550 Cold-cranking
Amperes Minimum Amperes Minimum Amperes Minimum
Weight 452 Pounds 470 Pounds 487 Pounds
Output Sound Level @ 23 ft (7m) at full load 68 db (A) 70.5db (A) 71.5 db (A)
Normal Operating Range -20°F (-28.8°C) to 104°F (40°C)
* Maximum wattage and current are subject to and limited by such factors as fuel Btu content, ambient temperature, altitude, engine power and condition, etc. Maximum power
decreases about 3.5 percent for each 1,000 feet above sea level; and also will decrease about 1 percent for each 6° C (10° F) above 16° C (60° F) ambient temperature.
** Load current values shown for 120 volts are maximum TOTAL values for two separate circuits. The maximum current in each circuit must not exceed the value stated for 240 volts.
† 15,000 watt with upgrade kit 04578-0. Kit includes power harnesses and 70 amp 2-pole circuit breaker.
1.5.2 ENGINE
Model 04389-1 Model 04456-1 Model 04390-1
Type of Engine GH-410 GT-990 GT-990
Number of Cylinders 1 2 2
Rated Horsepower 14.5 @ 3,600 rpm 26 @ 3,600 rpm 30 @ 3,600 rpm
Displacement 410cc 992cc 992cc
Cylinder Block Aluminum w/Cast Aluminum w/Cast Aluminum w/Cast
Iron Sleeve Iron Sleeve Iron Sleeve
Valve Arrangement Overhead Valves Overhead Valves Overhead Valves
Ignition System Solid-state w/Magneto Solid-state w/Magneto Solid-state w/Magneto
Recommended Spark Plug RC12YC RC12YC RC12YC
Spark Plug Gap 0.76 mm (0.030 inch) 0.508 mm (0.020 inch) 0.508 mm (0.020 inch)
Compression Ratio 8.6:1 9.5:1 9.5:1
Starter 12 Vdc 12 Vdc 12Vdc
Oil Capacity Including Filter Approx. 1.5 Qts Approx. 1.7 Qts Approx. 1.7 Qts
Recommended Oil Filter Generac Part # 70185 Generac Part # 70185 Generac Part # 70185
Recommended Air Filter Generac Part # 0C8127 Generac Part # 0C8127 Generac Part # 0C8127
Operating RPM 3,600 3,600 3,600
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Generac®Power Systems, Inc. 7
1.6 FUEL REQUIREMENTS
AND RECOMMENDATIONS
With LP gas, use only the vapor withdrawal
system. This type of system uses the vapors formed
above the liquid fuel in the storage tank.
The engine has been fitted with a fuel carburetion
system that meets the specifications of the 1997
California Air Resources Board for tamper-proof dual
fuel systems. The unit will run on natural gas or LP
gas, but it has been factory set to run on natural gas.
Should the primary fuel need to be changed to LP
gas, the fuel system needs to be reconfigured. See
Section 1.8 for instructions on reconfiguration of the
fuel system.
Recommended fuels should have a Btu content of at
least 1,000 Btus per cubic foot for natural gas; or at
least 2,520 Btus per cubic foot for LP gas. Ask the
fuel supplier for the Btu content of your fuel.
Fuel pressure for both natural gas and liquid
propane set ups should be 11 inches to 14 inches
of water column (0.6 psi) at all load ranges.
NOTE:
A seperate gas line and regulator may be needed
to assure proper gas pressure (11-14”) to the gen-
erator. Low gas pressure can cause hard starting
and could affect engine durability.
1.7 FUEL CONSUMPTION
*Natural gas is in cubic feet per hour.
**LP is in gallons per hour/cubic feet per hour.
Gaseous fuels such as natural gas and liquid
propane (LP) gas are highly explosive. Even the
slightest spark can ignite such fuels and cause
an explosion. No leakage of fuel is permitted.
Natural gas, which is lighter than air, tends to
collect in high areas. LP gas is heavier than air
and tends to settle in low areas.
1.8 RECONFIGURING THE
FUEL SYSTEM
1.8.1 7 KW, 410CC ENGINE
To reconfigure the fuel system from NG to LP,
follow these steps:
1. Turn the main gas supply off.
2. Remove the carburetor fuel hose from the outlet
port of the demand regulator (Figure 1.3).
3. Disconnect wire #0 and wire #14 from the gas
solenoid located on the top of the demand regu-
lator.
4. Remove the demand regulator by rotating coun-
terclockwise.
5. Remove the brass hose fitting from the outlet port
of the demand regulator.
6. Remove the brass metering jet (loosen counter-
clockwise) from the housing port of the demand
regulator located on the side of the regulator.
7. Install new LP metering jet (tighten clockwise) in
the outlet port of the demand regulator.
8. Refit the brass hose fittings to the outlet port of
the demand regulator.
9. Reverse procedure steps 1-4 to reinstall demand
regulator.
10. Reverse the procedure to convert back to natural
gas.
Figure 1.3 – Demand Regulator
NOTE:
The natural gas adjustment screw is preset during
installation and should not need any further
adjustment.
1.8.2 12KW AND 15KW, 990CC ENGINES
To reconfigure the fuel system from NG to LP,
follow these steps:
NOTE:
The primary regulator for the propane supply is
NOT INCLUDED with the generator. A fuel pres-
sure of 11 to 14 inches of water column (0.6 psi)
to the fuel inlet of the generator MUST BE SUP-
PLIED.
1. Turn OFF the main gas supply.
2. Remove the engine air in baffle located on the left
hand side of the battery compartment. Two M6
screws are located on top of the baffle and two
M6 screws are located on the inside of the baffle
towards the back.
◆
FUEL HOSE
BRASS HOSE
FITTING
FUEL JET
NG FUEL SYSTEM LP FUEL SYSTEM
FUEL HOSE
BRASS HOSE
FITTING
HOUSING
PORTS
HOUSING
PORTS
◆
DANGER
Section 1 — General Information
Guardian Air-cooled 7 kW, 12 kW and 15 kW Generators
Model # Nat. Gas (*) LP Vapor (**)
1/2 Load Full Load 1/2 Load Full Load
04389 74 105 0.91/33 1.21/44.1
04456 114 185 1.34/48.9 2.17/79.0
04390 148.5 240 1.73/63.2 2.80/102.3

3. Remove the small hose clamp and hose from the
fuel regulator. It may be necessary to pry the hose
off of the brass fitting using a screw driver to gen-
tly lift up the hose edge.
4. Remove the brass hose fitting screwed into the
fuel regulator.
5. Locate and identify the brass idle jet. This will be
located in the fuel regulator casting facing the
front of the unit.
6. Remove the idle jet from its holding location.
7. Place the idle jet, thread side first, into the
threaded hole originally occupied by the brass
hose fitting.
8. Using a short No. 2 Phillips screw driver, thread
the idle jet into the regulator casting. DO NOT
OVER TIGHTEN.
9. Apply thread sealant to the threads of the hose fit-
ting and replace it into the regulator body.
10. Re-attach the small hose and hose clamp and
tighten as necessary.
11. Replace the engine air in baffle using the four M6
screws.
12. Identify both brass adjustment screws on the reg-
ulator.
NOTE:
One adjustment screw can be accessed from the
front of the unit and the second can be accessed
from the back of the unit enclosure by removing
the plastic hole plug.
13. To adjust the system to run on LP fuel, turn the
adjuster screw that can be accessed from inside
the front of the unit, ¼ TURN CLOCKWISE. This
should now set the system for maximum power
and best performance.
14. It may be necessary to make minor adjustments
to the preset adjustment screw settings to achieve
maximum power. If experiencing problems with
the unit producing maximum power, follow the
procedure in Section 2.6 (Adjusting the Fuel
Regulator).
Figure 1.4 - Demand Regulator
1.9 LOCATION
1.9.1 GENERATOR
Install the generator set, in its protective enclosure,
outdoors, where adequate cooling and ventilating air
is always available. Consider these factors:
• Install the unit where air inlet and outlet openings
will not become obstructed by leaves, grass, snow,
etc. If prevailing winds will cause blowing or drift-
ing, consider using a windbreak to protect the unit.
• Install the generator on high ground where water
levels will not rise and endanger it.
• Allow sufficient room on all sides of the generator
for maintenance and servicing. A good rule is to
allow three feet of space on all sides.
• Where strong prevailing winds blow from one
direction, face the generator air inlet openings to
the prevailing winds.
• Install the generator as close as possible to the fuel
supply, to reduce the length of piping.
• Install the generator as close as possible to the
transfer switch. HOWEVER, REMEMBER THAT
LAWS OR CODES MAY REGULATE THE DIS-
TANCE.
The genset must be installed on a level surface. The
base frame must be level within two (2) inches all
around.
1.9.2 TRANSFER SWITCH
1.9.2.1 7 kW, 12 kW and 15 kW Units
The transfer switch shipped with this generator is
enclosed in a NEMA 1 enclosure. This type of enclo-
sure is intended for indoor use only. Follow these
rules:
• Install the transfer switch indoors on a firm, stur-
dy supporting structure.
• To prevent switch distortion, level the switch if nec-
essary. This can be done by placing washers
between the switch enclosure and mounting sur-
face.
• Never install the switch where water or any corro-
sive substance might drip onto the enclosure.
• Protect the switch at all times against excessive
moisture, dust, dirt, lint, construction grit and cor-
rosive vapors.
◆
◆
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Section 1 — General Information
Guardian Air-cooled 7 kW, 12 kW and 15 kW Generators
8 Generac®Power Systems, Inc.

Generac®Power Systems, Inc. 9
1.10 BATTERY INSTALLATION
Fill the battery with the proper electrolyte fluid if nec-
essary and have the battery fully charged before
installing it.
Before installing and connecting the battery, complete
the following steps:
1. Set the generator's Auto/Off/Manual switch to OFF.
2. Turn off utility power supply to the transfer
switch.
3. Remove the 5A and 15A fuses from the generator
control panel.
If the Auto/Off/Manual switch is not set to its
OFF position, the generator can crank and start
as soon as the battery cables are connected. If
the utility power supply is not turned off,
sparking can occur at the battery posts and
cause an explosion.
Battery cables were factory connected at the genera-
tor (Figure 1.5). Connect cables to battery posts as
follows:
4. Connect the red battery cable (from starter con-
tactor) to the battery post indicated by a positive,
POS or (+).
5. Connect the black battery cable (from frame
ground) to the battery post indicated by a nega-
tive, NEG or (—).
NOTE:
Damage will result if battery connections are made
in reverse.
Figure 1.5 – Battery Cable Connections
NOTE:
The generator is equipped with a battery trickle
charger that is active when the unit is set up for
automatic operation. With the battery installed
and utility power source voltage available to the
transfer switch, the battery receives a trickle
charge while the engine is not running, to prevent
self-discharge. The trickle charger is designed to
help extend the life of your battery by maintaining
the battery when the unit is not running. The
trickle charge feature cannot be used to recharge
a discharged battery.
1.11 THE BATTERY
Servicing of the battery is to be performed or super-
vised by personnel knowledgeable of batteries and
the required precautions. Keep unauthorized person-
nel away from batteries.
When replacing the battery, use the following type of
battery: Group 26/26R 12-volt DC, negative ground
battery with a rating of 350 cold-cranking amps min-
imum for 7 kW; 550 cold-cranking amps minimum
for 12 and 15 kW at -17.8º C (0º F) minimum. When
using a maintenance-free battery, it is not necessary
to check the specific gravity or electrolyte level. Have
these procedures performed at the intervals specified
in the “Service Schedule.” A negative ground system
is used. Battery connections are shown on the wiring
diagrams. Make sure the battery is correctly connect-
ed and terminals are tight. Observe battery polarity
when connecting the battery to the generator set.
Do not dispose of the battery in a fire. The
battery is capable of exploding.
A battery presents a risk of electrical shock
and high short circuit current. The following
precautions are to be observed when working
on batteries:
• Remove the 5A and 15A fuses from the generator
control panel.
• Remove watches, rings or other metal objects;
• Use tools with insulated handles;
• Wear rubber gloves and boots;
• Do not lay tools or metal parts on top of the
battery; and
• Disconnect charging source prior to connecting or dis-
connecting battery terminals.
Do not open or mutilate the battery. Released
electrolyte has been known to be harmful to
the skin and eyes, and to be toxic.
The electrolyte is a dilute sulfuric acid that is
harmful to the skin and eyes. It is electrically
conductive and corrosive.
The following procedures are to be observed:
• Wear full eye protection and protective clothing;
• Where electrolyte contacts the skin, wash it off
immediately with water;
!
!
DANGER
Section 1 — General Information
Guardian Air-cooled 7 kW, 12 kW and 15 kW Generators

10 Generac®Power Systems, Inc.
• Where electrolyte contacts the eyes, flush
thoroughly and immediately with water and seek
medical attention; and
• Spilled electrolyte is to be washed down with an
acid neutralizing agent. A common practice is to
use a solution of 1 pound (500 grams) bicarbonate
of soda to 1 gallon (4 liters) of water. The bicar-
bonate of soda solution is to be added until the
evidence of reaction (foaming) has ceased. The
resulting liquid is to be flushed with water and the
area dried.
Lead-acid batteries present a risk of fire
because they generate hydrogen gas. The
following procedures are to be followed:
• DO NOT SMOKE when near the battery;
• DO NOT cause flame or spark in battery area; and
• Discharge static electricity from your body before
touching the battery by first touching a grounded
metal surface.
Be sure the Auto/Off/Manual switch is set to
the OFF position before connecting the battery
cables. If the switch is set to AUTO or MANUAL,
the generator can crank and start as soon as
the battery cables are connected.
Be sure the utility power supply is turned off
and the 5A and 15A fuses are removed from
the generator control panel, or sparking may
occur at the battery posts as the cables are
attached and cause an explosion.
2.1 BEFORE INITIAL START-UP
Before starting, complete the following:
1. Set the generator’s main circuit breaker to its
OFF (or open) position.
2. Set the generator's Auto/Off/Manual switch to the
OFF position.
3. Turn OFF the utility power supply to the transfer
switch using the means provided (such as the
utility main line circuit breaker).
4. Turn OFF all loads connected to the transfer
switch terminals T1 and T2.
5. Check the engine crankcase oil level and, if nec-
essary, fill to the dipstick FULL mark with the
recommended oil. Do not fill above the FULL
mark.
6. Check the fuel supply. Gaseous fuel lines must have
been properly purged and leak tested in accor-
dance with applicable fuel-gas codes. All fuel shut-
off valves in the fuel supply lines must be open.
Never operate the engine with the oil level
below the “Add” mark on the dipstick. Doing
this could damage the engine.
2.2 CHECK TRANSFER SWITCH
OPERATION
Refer to Section 3.5, of the owner’s manual for man-
ual operation procedures.
Do not attempt manual transfer switch opera-
tion until all power voltage supplies to the
transfer switch have been positively turned off.
Failure to turn off all power voltage supplies
will result in extremely hazardous and possibly
fatal electrical shock.
2.3 ELECTRICAL CHECKS
Complete electrical checks as follows:
1. Set the generator's main circuit breaker to its
OFF (or open) position.
2. Set the generator's Auto/Off/Manual switch to the
OFF position.
3. Turn OFF all loads connected to the transfer
switch terminals T1 and T2.
4. Turn on the utility power supply to the transfer
switch using the means provided (such as a utili-
ty main line circuit breaker).
The transfer switch is now electrically “hot.”
Contact with “hot” parts will result in extreme-
ly hazardous and possibly fatal electrical shock.
Proceed with caution.
5. Use an accurate AC voltmeter to check utility
power source voltage across transfer switch ter-
minals N1 and N2. Nominal line-to-line voltage
should be 240 volts AC.
6. Check utility power source voltage across termi-
nals N1 and the transfer switch neutral lug; then
across terminal N2 and neutral. Nominal line-to-
neutral voltage should be 120 volts AC.
7. When certain that utility supply voltage is com-
patible with transfer switch and load circuit rat-
ings, turn OFF the utility power supply to the
transfer switch.
8. On the generator panel, set the Auto/Off/Manual
switch to MANUAL. The engine should crank and
start.
9. Let the engine warm up for about five minutes to
allow internal temperatures to stabilize. Then, set
the generator’s main circuit breaker to its ON (or
closed) position.
Proceed with caution! Generator power voltage
is now supplied to the transfer switch. Contact
with live transfer switch parts will result in
dangerous and possibly fatal electrical shock.
DANGER
DANGER
DANGER
!
!
Section 2 — Post Installation Start-up and Adjustments
Guardian Air-cooled 7 kW, 12 kW and 15 kW Generators

Generac®Power Systems, Inc. 11
10. Connect an accurate AC voltmeter and a frequen-
cy meter across transfer switch terminal lugs E1
and E2. Voltage should be 242-252 volts; fre-
quency should read about 61-63 Hertz.
11. Connect the AC voltmeter test leads across termi-
nal lug E1 and neutral; then across E2 and neu-
tral. In both cases, voltage reading should be 121-
126 volts AC.
12. Set the generator’s main circuit breaker to its
OFF (or open) position. Let the engine run at no-
load for a few minutes to stabilize internal engine
generator temperatures.
13. Set the generator's Auto/Off/Manual switch to
OFF. The engine should shut down.
NOTE:
It is important not to proceed until you are certain
that generator AC voltage and frequency are cor-
rect and within the stated limits. Generally, if both
AC frequency and voltage are high or low, the
engine governor requires adjustment. If frequency
is correct, but voltage is high or low, the genera-
tor’s voltage regulator requires adjustment.
2.4 GENERATOR TESTS UNDER LOAD
To test the generator set with electrical loads applied,
proceed as follows:
1. Set generator’s main circuit breaker to its OFF
(or open) position.
2. Turn OFF all loads connected to the transfer
switch terminals T1 and T2.
3. Set the generator's Auto/Off/Manual switch to OFF.
4. Turn OFF the utility power supply to the transfer
switch, using the means provided (such as a util-
ity main line circuit breaker).
Do not attempt manual transfer switch opera-
tion until all power voltage supplies to the
transfer switch have been positively turned off.
Failure to turn off all power voltage supplies
will result in extremely hazardous and possibly
fatal electrical shock.
5. Manually set the transfer switch to the STANDBY
position, i.e., load terminals connected to the
generator's E1/E2 terminals. The transfer switch
operating lever should be down.
6. Set the generator's Auto/Off/Manual switch to
MANUAL. The engine should crank and start
immediately.
7. Let the engine stabilize and warm up for a few
minutes.
8. Set the generator’s main circuit breaker to its ON
(or closed) position. Loads are now powered by
the standby generator.
9. Turn ON electrical loads connected to transfer
switch T1 and T2. Apply an electrical load equal
to the full rated wattage/amperage capacity of the
installed generator.
10. Connect an accurate AC voltmeter and a frequen-
cy meter across terminal lugs E1 and E2. Voltage
should be greater than 230 volts; frequency
should be greater than 58 Hertz.
11. Let the generator run at full rated load for 20-30
minutes. Listen for unusual noises, vibration or
other indications of abnormal operation. Check
for oil leaks, evidence of overheating, etc.
12. When testing under load is complete, turn OFF
electrical loads.
13. Set the generator's main circuit breaker to its
OFF (or open) position.
14. Let the engine run at no-load for a few minutes.
15. Set the Auto/Off/Manual switch to OFF. The
engine should shut down.
2.5 CHECKING AUTOMATIC
OPERATION
To check the system for proper automatic operation,
proceed as follows:
1. Set generator’s main circuit breaker to its OFF
(or open) position.
2. Check that the Auto/Off/Manual switch is set to
OFF.
3. Turn OFF the utility power supply to the transfer
switch, using means provided (such as a utility
main line circuit breaker).
4. Manually set the transfer switch to the UTILITY
position, i.e., load terminals connected to the util-
ity power source side.
5. Turn ON the utility power supply to the transfer
switch, using the means provided (such as a util-
ity main line circuit breaker).
6. Set the Auto/Off/Manual switch to AUTO. The sys-
tem is now ready for automatic operation.
7. Turn OFF the utility power supply to the transfer
switch.
With the Auto/Off/Manual switch at AUTO, the engine
should crank and start when the utility source power
is turned OFF. After starting, the transfer switch
should connect load circuits to the standby side. Let
the system go through its entire automatic sequence
of operation.
With the generator running and loads powered by
generator AC output, turn ON the utility power sup-
ply to the transfer switch. The following should
occur:
• After about six seconds, the switch should transfer
loads back to the utility power source.
• About one minute after retransfer, the engine
should shut down.
Section 2 — Post Installation Start-up and Adjustments
Guardian Air-cooled 7 kW, 12 kW and 15 kW Generators

12 Generac®Power Systems, Inc.
2.6 ADJUSTING THE REGULATOR
(NATURAL GAS ONLY)
Although the generator has been factory set to pro-
vide maximum power, it may be necessary in some
areas to adjust this setting. Because natural gas has
different BTU or power content across the country
the engine may not perform as designed.
If experiencing engine problems at high or full load
conditions follow these steps. It will require a fre-
quency meter to perform this procedure.
1. Turn off utility power to the main distribution
panel in the house. This can be done by switching
the service main breaker to the off or open posi-
tion.
2. Allow the generator to start. Before loading the
generator, confirm that the No Load Frequency,
with the roof open and door off, is set to 63-63.5
Hz. Transfer load to emergency circuits.
3. Turn on appliances, lights, pumps, etc., that are
on the emergency circuits in an attempt to fully
load the generator. Be cautious not to overload
the generator. Use the following chart as a guide:
4. When full load has been achieved. Connect a fre-
quency meter to the output lugs of the generator’s
main line circuit breaker.
5. The fuel regulator is fitted with one (7 kW), or two
(12 & 15 kW) adjustment screws. While watching
the frequency meter, slowly turn the adjustment
screws clockwise or counterclockwise one at a
time until the highest frequency is read on the
meter. Only limited adjustment is available
between the set pins (7 kW only). Under no cir-
cumstances should any of the pins be removed
(Figures 2.1 and 2.2).
Figure 2.1 — Dual Fuel Regulators
6. When the highest frequency is reached maximum
power has been set. From this point turn both
adjustment screws 1/4 turn counterclockwise.
The regulator is now set.
Figure 2.2 — Placement of Regulator
7. Turn utility power to the main distribution panel
back on. This can be done by switching the serv-
ice main breaker to the on or closed position.
Allow the generator to shut down.
Do not make any unnecessary adjustments.
Factory settings are correct for most applica-
tions. However, when making adjustments, be
careful to avoid overspeeding the engine.
If this procedure or equipment are not available to
you, locate the nearest Generac Guardian Dealer
nearest and they can perform the adjustments.
NOTE:
A service fee may be charged for this adjustment.
2.7 ENGINE GOVERNOR ADJUSTMENT
If both AC frequency and voltage are correspondingly
high or low, adjust the engine governor as follows:
2.7.1 7 KW UNITS
1. Loosen the governor clamp bolt (Figures 2.3).
2. Hold the governor lever at its wide open throttle
position, and rotate the governor shaft clockwise
as far as it will go. Then, tighten the governor
lever clamp bolt to 70 inch-pounds (8 N-m).
3. Start the generator; let it stabilize and warm up
at no-load.
4. Connect a frequency meter across the generators
AC output leads.
◆
!
Adjustment Screw
410
Adjustment
Screw
(One Side
Only)
Set
Pins
990
Adjustment
Screw
(Both sides)
Section 2 — Post Installation Start-up and Adjustments
Guardian Air-cooled 7 kW, 12 kW and 15 kW Generators
Unit 120 Volts 240 Volts
7 kW 50.0 amps 25.0 amps
12 kW 100.0 amps 50.0 amps
15 kW 108.3 amps 54.1 amps

Generac®Power Systems, Inc. 13
Section 2 — Post Installation Start-up and Adjustments
Guardian Air-cooled 7 kW, 12 kW and 15 kW Generators
5. Turn the speed adjust nut to obtain a frequency
reading of 63 Hz.
6. When frequency is correct at no load, check the
AC voltage reading. If voltage is incorrect, the volt-
age regulator may require adjustment.
Figure 2.3 — Engine Governor Adjustment
2.7.2 12 KW AND 15 KW UNITS
1. Loosen governor clamp bolt (See Figure 2.3).
2. Completely remove the idle spring.
3. With governor arm at wide open throttle position,
rotate governor shaft fully clockwise. Tighten
clamp bolt to 84 inch-pounds.
4. Start unit and apply full load. Use full load speed
adjust screw (Figure 2.4) to adjust frequency to
58 Hz.
5. Remove load, stop engine, loosen the idle adjust
screw and reconnect the idle spring.
Figure 2.4 — Full Load Speed Adjust Screw
6. Using a hand, push the governor arm to the
closed throttle position. Make sure the idle spring
does not stretch at all.
7. Restart the unit.
8. Slowly turn the idle adjust screw to adjust the no-
load idle frequency to 63-63.5 Hz (with door
open).
9. The governor is now set.
2.7.3 ADDITIONAL CORROSION
PROTECTION
Periodically spray all engine linkage parts and brack-
ets with corrosion inhibiting spray such as WD-40 or
a comparable product.
2.8 VOLTAGE REGULATOR
ADJUSTMENT
With the frequency between 62-63 Hertz, slowly turn
the slotted potentiometer (Figure 2.5) until line volt-
age reads 247-252 volts.
NOTE:
The access panel on top of the control panel must
be removed to adjust the voltage regulator.
Figure 2.5 – Voltage Adjustment Potentiometer
NOTE:
The voltage regulator is housed above the genera-
tor's control panel. The regulator maintains a volt-
age in direct proportion to frequency at a 2-to-1
ratio. For example, at 62 Hertz, line-to-neutral
voltage will be 124 volts.
◆
Full Load Speed Adjust Screw
◆
Governor Clamp Bolt
Governor
Shaft
(Rotate
Clockwise)
Idle Spring
No Load Idle
Adjustment Screw

14 Generac®Power Systems, Inc.
Section 3 — Operation
Guardian Air-cooled 7 kW, 12 kW and 15 kW Generators
3.1 BREAK-IN PROCEDURE
Once the unit has been installed and all electrical
checks have been made, it is strongly recommended
that the following “Break-in Procedure” be completed
to ensure correct generator operation in the future.
1. Set the generator’s Auto/Off/Manual switch to
AUTO.
2. Turn OFF the utility power supply to the transfer
switch using the means provided (such as a utili-
ty main line circuit breaker).
3. The unit will start, and the transfer switch will
transfer to standby.
4. Using the transfer switch’s built-in emergency
load center, turn on circuits to load the generator
to approximately 25% rated load and run the unit
for one hour.
5. Run the unit for one hour at 50% rated load.
6. Run the unit for one hour at 75% rated load.
7. Run the unit for one hour at 100% rated load.
8. Turn ON the utility power supply to the transfer
switch, which will allow the transfer switch to
transfer back to utility power. The unit will con-
tinue to run for one minute and then shut down.
9. Allow the unit to cool.
10. Set the generator's Auto/Off/Manual switch to
OFF. Remove the 5A and 15A fuses from the gen-
erator control panel. Disconnect the battery
cables as outlined in “General Hazards” (page 2).
11. Drain the oil and remove the oil filter. Replace the
oil filter according to Section 4.4, “Changing the
Oil Filter”. Replace the oil with synthetic oil as
recommended in Section 4.3, “Changing the
Engine Oil”.
12. Reconnect the battery cables as outlined in
“General Hazards” (page 2) and insert the 5A and
15A fuses into the generator control panel. The
generator is now ready for service.
3.2 USING THE AUTO/OFF/MANUAL
SWITCH (FIGURE 3.1)
3.2.1 “AUTO” POSITION
Selecting this switch position activates fully automat-
ic system operation. It also allows personnel to start
and exercise the engine every seven days with the set-
ting of the exercise timer (see Section 3.6). This posi-
tion also is used for remote starting, when it is set up.
3.2.2 “OFF” POSITION
This switch position shuts down the engine. This
position also prevents automatic operation.
3.2.3 “MANUAL” POSITION
Set the switch to Manual to crank and start the
engine. Transfer to standby power will not occur
unless there is a utility failure.
Figure 3.1 – Generator Control Panel
With the switch set to AUTO, the engine may
crank and start at any time without warning.
Such automatic starting normally occurs when
utility power source voltage drops below a pre-
set level or during the normal exercise cycle. To
prevent possible injury that might be caused by
such sudden starts, always set the switch to
OFF and remove the fuses before working on
or around the generator or transfer switch.
Then, place a “DO NOT OPERATE” tag on the
generator panel and on the transfer switch.
3.3 AUTOMATIC TRANSFER
OPERATION
To select automatic operation, do the following:
1. Make sure the transfer switch main contacts are
set to their “Utility” position, i.e., loads connected
to the utility power source (Figure 3.2).
2. Be sure that normal utility power source voltage
is available to transfer switch terminal lugs N1
and N2.
3. Set the generator’s Auto/Off/Manual switch to
AUTO.
4. Set the generator’s main circuit breaker to its ON
(or closed) position.
With the preceding steps complete, the generator will
start automatically when utility source voltage drops
below a preset level. After the unit starts, loads are
transferred to the standby power source. Refer to
Section 3.4, “Sequence of Automatic Operation.”
!
HIGH TEMP.
OVER SPEED
LOW OIL
SYSTEM SET
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MAN.
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15A
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EXERCISE
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RPOWER SYSTEMS, INC.
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



Generac®Power Systems, Inc. 15
3.4 SEQUENCE OF AUTOMATIC
OPERATION
The generator’s control panel houses a control logic
circuit board. This board constantly monitors utility
power source voltage. Should that voltage drop below
a preset level, circuit board action will signal the
engine to crank and start. After the engine starts, the
circuit board signals the transfer switch to activate
and connect load circuits to the standby power sup-
ply (load terminal lugs T1/T2 connect to terminal
lugs E1/E2).
Upon restoration of utility source voltage above a pre-
set level, generator circuit board action signals the
transfer switch to transfer loads back to that power
supply. After retransfer, the engine is signalled to shut
down.
The actual sequence of operation is controlled by
sensors and timers on a control logic circuit board,
as follows:
A. Utility Voltage Dropout Sensor
• This sensor monitors utility source voltage.
• If utility source voltage drops below about 70 per-
cent of the nominal supply voltage, the sensor
energizes a 15-second timer.
• Once the timer has expired, the engine will crank
and start.
B.Engine Warm-up Time Delay
• This mechanism lets the engine warm up for
about 10 seconds before the load is transferred
to the standby source.
C.Standby Voltage Sensor
• This sensor monitors generator AC output volt-
age. When the voltage has reached 50 percent of
the nominal rated voltage, transfer to standby
can occur.
D.Utility Voltage Pickup Sensor
• This sensor monitors utility power supply volt-
age. When that voltage is restored above 70 per-
cent of the nominal source voltage, a retransfer
time delay starts timing.
E.Retransfer Time Delay
• This timer runs for about 15 seconds.
• At end of a 15-second delay, circuit board action
de-energizes transfer relay in the transfer switch.
• Retransfer to utility power source then occurs.
F. Engine Cool-down Timer
• When the load is transferred back to utility power
source, the engine cool-down timer starts timing.
• The timer will run for about one minute, and the
generator will then shut down.
3.5 MANUAL TRANSFER OPERATION
3.5.1 TRANSFER TO GENERATOR
POWER SOURCE
To start the generator and activate the transfer switch
manually, proceed as follows:
1. Set the generator’s Auto/Off/Manual switch
to OFF.
2. Set the generator’s main circuit breaker to its
OFF (or open) position.
3. Turn OFF the utility power supply to the transfer
switch using the means provided (such as a
utility main line circuit breaker).
Do not attempt to activate the transfer switch
manually until all power voltage supplies to
the switch have been positively turned off.
Failure to turn off all power voltage supplies
may result in extremely hazardous and possibly
fatal electrical shock.
4. Use the manual transfer handle inside the trans-
fer switch to move the main contacts to their
“Standby” position, i.e., loads connected to the
standby power source (Figure 3.2).
Figure 3.2 – Manual Transfer Switch Operation
5. To crank and start the engine, set the
Auto/Off/Manual switch to MANUAL.
6. Let the engine stabilize and warm up for a few
minutes.
7. Set the generator’s main circuit breaker to its ON
(or closed) position. The standby power source
now powers the loads.
DANGER

Section 3 — Operation
Guardian Air-cooled 7 kW, 12 kW and 15 kW Generators

16 Generac®Power Systems, Inc.
3.5.2 TRANSFER BACK TO UTILITY POWER
SOURCE
When utility power has been restored, transfer back
to that source and shut down the generator. This can
be accomplished as follows:
1. Set the generator’s main circuit breaker to its
OFF (or open) position.
2. Let the engine run for a minute or two at no-load
to stabilize the internal temperatures.
3. Set the generator’s Auto/Off/Manual switch to
its OFF (or open) position. The engine should
shut down.
4. Check that utility power supply to the transfer
switch is turned OFF.
Do not attempt to activate the transfer switch
manually until all power voltage supplies
to the switch have been positively turned off.
Failure to turn off all power voltage supplies
may result in extremely hazardous and possibly
fatal electrical shock.
5. Use the manual transfer handle inside the trans-
fer switch to move the main contacts back to their
“Utility” position, i.e., loads connected to the util-
ity power source (Figure 3.2).
6. Turn ON the utility power supply to the transfer
switch using the means provided.
7. Set the system to automatic operation as outlined
in “Automatic Transfer Operation,” Section 3.3.
3.6 SETTING THE EXERCISE TIMER
This generator is equipped with an exercise timer.
Once it is set, the generator will start and exercise
once every seven days, on the day of the week and at
the time of day the following sequence is completed.
During this exercise period, the unit runs for approx-
imately 12 minutes and then shuts down. Transfer of
loads to the generator output does not occur during
the exercise cycle.
A switch on the control panel (see Figure 3.1) permits
selection of the day and time for the system to exer-
cise. At the chosen time, perform the following
sequence to select the desired day and time of day the
system will exercise.
1. Verify that the Auto/Off/Manual switch is set
to AUTO.
2. Hold down the “Set Exercise Time” switch until
the generator starts (approximately 10 seconds)
and then release.
3. The generator will start and run for approximate-
ly 12 minutes and then shut down on its own.
The exerciser will then be set to run at that time
of day every week.
NOTE:
The exerciser will only work in the AUTO mode
and will not work unless this procedure
is performed. The exerciser will need to be reset
every time the 12-volt battery is disconnected and
then reconnected. The exerciser WILL NOT work
if dip switch 2 on the controller printed circuit
board (Remote Not Auto) is ON.
3.7 PROTECTION SYSTEMS
3.7.1 LOW OIL PRESSURE SWITCH
This switch (Figure 3.3) has normally closed contacts
that are held open by engine oil pressure during
cranking and operating. Should oil pressure drop
below the 8 psi range, switch contacts close, and the
engine shuts down. The unit should not be restarted
until oil is added. The Auto/Off/Manual switch must
then be turned to OFF and then back to AUTO.
3.7.2 HIGH TEMPERATURE SWITCH
This switch’s contacts (Figure 3.3) close if the tem-
perature should exceed approximately 140º C (284º
F), initiating an engine shutdown. The generator will
automatically restart and the LED on the generator
control panel will reset once the temperature has
returned to a safe operating level.
Figure 3.3 – Low Oil Pressure and
High Temperature Switches
3.7.3 OVERCRANK
This feature prevents the generator from damaging
itself when it continually attempts to start and anoth-
er problem, such as no fuel supply, prevents it from
starting. The unit will crank and rest for a preset time
limit. Then, it will stop cranking, and the LED on the
generator control panel will light indicating an over-
crank failure. The Auto/Off/Manual switch will need
to be set to OFF and then back to AUTO to reset the
generator control board.
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Oil Filter
Oil
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Section 3 — Operation
Guardian Air-cooled 7 kW, 12 kW and 15 kW Generators

Generac®Power Systems, Inc. 17
NOTE:
If the fault is not repaired, the overcrank feature
will continue to activate.
3.7.3.1 Approximate Crank Cycle Times
• 15 seconds ON
• 7 seconds OFF
• 7 seconds ON
• 7 seconds OFF
• Repeat for 45 seconds
Approximately 90 seconds total
3.7.4 OVERSPEED
This feature protects the generator from damage by
shutting it down if it happens to run faster than the
preset limit. This protection also prevents the gener-
ator from supplying an output that could potentially
damage appliances connected to the generator
circuit. Contact the nearest Generac/Guardian
Authorized Dealer if this failure occurs.
4.1 FUSE
The generator panel’s 15 amp fuse (Figure 4.1) pro-
tects the DC control circuit against overload. The fuse
is wired in series with the battery output lead to the
panel. If the fuse element has melted open, the engine
cannot crank or start. Replace the fuse using only an
identical 15-amp replacement.
The generator panel’s 5 amp fuse protects the battery
charge circuit against overload. If the fuse element
has melted open, there will not be battery charging
capabilities. Replace the fuse using only an identical
5 amp replacement. To remove fuse, push cap down
and rotate counterclockwise.
Figure 4.1 – Generator Control Panel
4.2 CHECKING THE ENGINE
OIL LEVEL
For oil capacities, see “Specifications,” Section 1.5.
For engine oil recommendations, see Section 4.3.1.
To check the engine oil level, proceed as follows
(Figures 4.2 and 4.3):
1. Start the generator by moving the Auto/
Off/Manual switch to the MANUAL position. Allow
it to run for a short while and then shut it down
by moving the switch to the OFF position.
2. Remove the dipstick and wipe it dry with a
clean cloth.
3. Install the dipstick; then, remove it again. The oil
level should be at the dipstick “Full” mark. If nec-
essary, add oil to the “Full” mark only. DO NOT
FILL ABOVE THE “FULL” MARK.
Never operate the engine with the oil level
below the “Add” mark on the dipstick. Doing
this could damage the engine.
4. Install the dipstick.
5. Reset the Auto/Off/Manual switch to its original
position.
Figure 4.2 — Oil Dipstick and Fill, 7 kW
Figure 4.3 — Oil Dipstick and Fill,
12 kW and 15 kW
Oil Dipstick
Oil Fill
Oil Dipstick and Fill
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HIGH TEMP.
OVER SPEED
LOW OIL
SYSTEM SET
OVER CRANK
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EXERCISE
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Section 4 — Maintenance
Guardian Air-cooled 7 kW, 12 kW and 15 kW Generators

18 Generac®Power Systems, Inc.
4.3 CHANGING THE ENGINE OIL
4.3.1 ENGINE OIL RECOMMENDATIONS
Use oil of American Petroleum Institute (API) Service
Class SG, SH or SJ. Use all season SAE 5W-30
Synthetic oil. Organic break-in oil is required before
using synthetic oil.
NOTE:
The unit is supplied with “break-in” oil. See the
“Break-in Procedure,” Section 3.1, for the first
required oil change.
Any attempt to crank or start the engine before
it has been properly serviced with the recom-
mended oil may result in an engine failure.
4.3.2 OIL CHANGE PROCEDURE
To change the oil, proceed as follows:
1. Run the engine until it is thoroughly warmed up
then shut OFF the engine.
2. Immediately after the engine shuts OFF, pull the
oil drain hose (Figure 4.4) free of its retaining
clip. Remove the cap from the hose and drain the
oil into a suitable container.
3. After the oil has drained, replace the cap onto the
end of the oil drain hose. Retain the hose in the clip.
4. Refill with the proper recommended oil (see
Section 4.3.1). See Section 1.5.2 for oil capaci-
ties.
Figure 4.4 – Oil Drain Hose and Filter
4.4 CHANGING THE OIL FILTER
Change the engine oil filter as follows:
1. With the oil drained, remove the old oil filter by
turning it counterclockwise.
2. Apply a light coating of clean engine oil to the gas-
ket of the new filter. See Section 1.5.1 for recom-
mended filter.
3. Screw the new filter on by hand until its gasket
lightly contacts the oil filter adapter. Then, tight-
en the filter an additional 3/4 to one turn (Figure
4.4).
4. Refill with the proper recommended oil (see
Section 4.3.1). See Section 1.5.2 for oil capaci-
ties.
5. Start the engine and check for leaks.
4.5 CHANGING THE ENGINE
AIR CLEANER
4.5.1 7 KW, 12 KW AND 15 KW
GENERATORS
See Figures 1.1 and 1.2, for the location of your air
cleaner. Use the following procedure (Figure 4.6):
1. Turn the two screws counterclockwise to loosen.
2. Remove the cover and air filter.
3. Wipe away dust or debris from inside of the air
box and around edges.
4. Install the new air cleaner into the air box.
5. Install the cover. Turn the two cover screws clock-
wise to tighten.
See the “Service Schedule,” Section 4.13, for air
cleaner maintenance. See Section 1.5.1 for air filter
replacement part number.
Figure 4.6 — 7 kW, Engine Air Cleaner Location
Air Cleaner
Fuel
Regulator
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Oil Filter
Oil
Drain
Hose
Low Oil Switch High Temp Switch
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Section 4 — Maintenance
Guardian Air-cooled 7 kW, 12 kW and 15 kW Generators