Generac Power Systems NP-66LPG Series User manual

Air-cooled Recreational
Vehicle Generator
OWNER'S MANUAL
GENERAC
CORPORATION
Model No. 9734-3 Series NP-66LPG Manual No. A4081
THIS SYMBOL POINTS OUT IMPORTANT SAFETY INSTRUCTIONS. WHICH. IF NOT FOLLOWED. COULD ENDANGER THE
PERSONAL SAFETY AND/OR PROPERTY OF YOURSELF AND OTHERS. READ AND FOLLOW ALL INSTRUCTIONS IN THE
MANUAL BEFORE ATTEMPTING TO OPERATE THIS UNIT.
Revision 1 (9/18/97)
Printed in U.S.A.

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Generac NP-66LPG Recreational Vehicle Generator
THE MANUFACTURER SUGGESTS THAT THESE “RULES” FOR SAFE OPERATION BE COPIED AND
POSTED IN POTENTIAL HAZARD AREAS OF THE RECREATIONAL VEHICLE. SAFETY SHOULD BE
STRESSED TO ALL OPERATORS AND POTENTIAL OPERATORS OF THIS EQUIPMENT.
Study these SAFETY RULES carefully before operating or ser¬
vicing applicable equipment. Become familiar with this Owner's
Manual and with your generator. Safe, efficient and reliable
operation can only be achieved if generator is properly installed,
operated and maintained. Many accidents are caused by fail¬
ing to follow simple and fundamental rules or precautions. The
manufacturer suggests that these GENERAL SAFETY RULES
be copied and posted in potential hazard areas of the recreational
vehicle. Safety should be stressed to all operators and poten¬
tial operators of equipment.
The manufacturer cannot possibly anticipate every circum¬
stance that might involve a hazard. The warnings in this Manual
and on tags and decals affixed to the unit are, therefore, not all-
inclusive. If you use a procedure, work method or operating
technique Generac does not specifically recommend, you must
satisfy yourself that it is safe for you and others. You must also
make sure the procedure, work method or operating technique
that you chose does not render the generator to be unsafe.
□ WARNING: 0
The engine exhaust from this product
contains chemicals known to the State
of California to cause cancer, birth
defects, or other reproductive harm.
• For fire safety, the recreational vehicle generator must be properly
installed and maintained. Installation must always remain in com¬
pliance with applicable codes and standards. In addition, the
generator must be installed in conformance to the manufacturer's
detailed installation instructions. Following installation, nothing must
be done that might render the generator in noncompliance with such
codes, standards and instructions.
• The RV generator produces extremely high and dangerous elec¬
trical voltages and can cause dangerous, and possibly fatal, electrical
shock. Avoid contact with bare wires, terminals, etc. while the unit
is running. If you must work around an operating generator, stand
on an insulated, dry surface to reduce shock hazard.
• Never work on this equipment or handle any electrical device while
standing in water, while barefoot, or while hands or feet are wet.
Dangerous electrical shock will result.
• Have the generator properly grounded (bonded) during installation
onto the vehicle, either by solid mounting to the vehicle frame or
chassis or by means of an approved bonding conductor. DO NOT
disconnect the bonding conductor, if so equipped. DO NOT recon¬
nect the bonding conductor to any generator part that might be
removed or disassembled during routine maintenance. If the ground¬
ing conductor must be replaced, use only a flexible conductor that
is of No. 8 AWG copper wire minimum.
In case of accident caused by electric shock, shut down the source
of electrical power down at once. If this cannot be done, free victim
from live conductor. AVOID DIRECT CONTACT WITH THE VICTIM.
Use a dry board, dry rope, or other non-conducting implement to
free the victim from live conductor.
Inspect fuel system frequently for leaks or damage. Repair or
replace any damaged or leaking component immediately. Never
attempt to change, alter or modify the generator fuel system in any
way that might affect safety or compliance with applicable codes
and standards.
The generator engine gives off DEADLY carbon monoxide gas
through its exhaust system. This dangerous gas, if breathed in suf¬
ficient concentrations, can cause unconsciousness or even death.
This exhaust system must have been properly installed, in strict com¬
pliance with applicable codes and standards. Following installation,
you must do nothing that might render the system unsafe or in non-
compliance with such codes and standards. The generator
compartment must be completely vapor sealed from vehicle inte¬
rior. There must be no possibility of exhaust fumes entering the
vehicle interior. Never operate this equipment with a leaking or
defective exhaust system.
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,
fuel leakage, oil leakage, etc.
Do not smoke around the generator. Wipe up any fuel, and oil
immediately Never leave oily or fuel soaked rags in the generator
compartment or on the generator itself. Keep the area around the
generator clean and free of debris.
Adequate ventilation is required to expel toxic fumes and gasoline
vapors from the generator compartment. Do not alter the installa¬
tion of this equipment in any manner that might obstruct air and
ventilation openings. Such openings must be kept clear and unob¬
structed.
Keep hands, feet, clothing, etc., away from drive belts, fans and other
moving parts of this equipment. Never remove any drive belt or fan
guards while the unit is operating.
Inspect the generator periodically. Repair or replace all damaged
or defective parts immediately.
This generator uses LP gas (propane) as a fuel. Liquid Propane
gas is highly EXPLOSIVE. The gas is heavier than air and tends
to settle in low areas where even the slightest spark can ignite the
gas and cause an explosion.
Before performing any maintenance on the generator set, discon¬
nect its battery cables to prevent accidental start up. Disconnect
the cable from the battery post indicated by a NEGATIVE, NEG or
(-) first. Reconnect that cable last.
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Generac NP-66LPG Recreational Vehicle Generator
Please record the following information from the generator DATA PLATE or information decal.
1. M odel Number_ 2. Serial Number_
3.kW Rating. 4. Rated Voltage.
5. Phase
6. Hertz.
REFERENCE NUMBER IDENTIFICATION
1. Generator Air Intake Screen
2. Engine Start/Stop Switch
3. Fuse
4. Circuit Breaker
5. Optional Remote Panel Receptacle
6. Generator AC Output Leads
7. Circuit Breaker
8. 12 Volts Battery Connection iq,
9. Fuel Primer Switch
10. Fuel Solenoid
11. Pressure Regulator
12. Oil Filter
13. Oil Drain Plug
14. Oil Dipstick and Filler Tube
Recreational Vehicle Generator

Generac NP-66LPG Recreational Vehicle Generator
GENERAL SAFETY RULES.2
IDENTIFICATION RECORD.3
GENERATOR FEATURES.3
READ THIS MANUAL
Operation and Maintenance.5
How to Obtain Sen/ice.5
GENERATOR FAMILIARIZATION
Generator Applicability.6
Installation.6
Safety.6
Generator AC Connection System.6
OPERATING INSTRUCTIONS.7-11
Generator Control Panel.7
Optional Remote Start/Stop Panel.7
Before Starting the Engine.8
Starting.8
Stopping the Generator.8
Applying Loads to Generator.9
Don’t Overload the Generator.9
Additional Information.10-11
SPECIFICATIONS
Fuel Requirements.. 1 2
Engine Oil Requirements. 12
Generator Specifications..12
13-16
.13
.13
.13
.14
.14
.14
15-16
.16
.16
.17
REPAIR PARTS.18-27
ELECTRICAL DATA.28
EMMISSIONS WARRANTY...:....30-31
BASIC 3-YEAR WARRANTY.back page
MAINTENANCE..
Checking Engine Oil Level.
Change Engine Oil.
Change oil filter.
Engine Air Cleaner.
Spark Arrestor Muffler.
Engine Spark Plugs.
Miscellaneous Maintenance.
Out of Service Protection.
Return the Unit to Service after Storage
TROUBLESHOOTING.
Recreational Vehicle Generator

Gensrac NP-66LPG Recreational Vehicle Generator
If you don't understand any portion of this manual, contact Gen-
erac for a demonstration of actual starting, operating and
servicing procedures.
Throughout this publication and on tags and decals affixed to
the generator, DANGER and CAUTION blocks are used to alert
you to special instruction about a particular operation that may
be hazardous if performed incorrectly or carelessly. Observe
them carefully.
These safety warnings cannot eliminate the hazards that they
indicate. Strict compliance with the special instructions while
performing the service plus ‘common sense” are major mea¬
sures to prevent accidents.
The following definitions apply to DANGER, CAUTION and
NOTE blocks found throughout the manual.
DANGER: AFTER THIS HEADING YOU CAN READ
HANDLING, INSTALLING, OPERATING OR SERVIC¬
ING INSTRUCTIONS THAT, IF NOT STRICTLY
COMPLIED WITH, MAY RESULT IN PERSONAL
INJURY.
CAUTION: After this heading you can read instruc¬
tions for handling, installing, operating or servicing
the generator that, if not strictly complied with, may
result in damage to equipment and/or property.
NOTE: After this heading you can read explanatory statements
that require special emphasis.
These symbols indicate the following:
Points out important safety information and, if not fol¬
lowed, could endanger personal safety and/or property
of yourself and others.
Potential explosion hazard
Potential fire hazard
The operator (driver) is responsible for proper and safe use-
of the vehicle, equipment on the vehicle, and the safety of all
vehicle occupants. We strongly recommend that the operator
read this Owner's Manual and thoroughly understand all
instructions before using this equipment. We also strongly rec¬
ommend instructing other occupants in the vehicle to properly
start and operate the generator. This prepares them if-they
need to operate the equipment in an emergency.
OPERATION AND MAINTENANCE
It is the operator's responsibility to perform all safety checks;
to make sure that all maintenance for safe operation is per¬
formed promptly; and to have the equipment checked by an
Authorized Dealer periodically. Normal maintenance 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. Indi¬
vidual operating habits and usage contribute to the need for
maintenance service.
Proper maintenance and care of your industrial mobile gen¬
erator assures a minimum number of problems and keeps your
operating expenses at a minimum. See your authorized
Dealer/Distributor for service aids and accessories.
HOW TO OBTAIN SERVICE
When your recreational vehicle generator set requires servicing
or repairs, simply contact an Authorized Service Facility for
assistance. Service technicians are factory-trained and are
capable of handling all of your service needs.
When contacting an Authorized Service Facility 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.
The warranty on your generator is included in this Owner's
Manual, as well as listings for repair parts.
Potential electrical shock hazard
Recreational Vehicle Generator

GENERATOR APPLICABILITY
These generators have been designed and manufactured for
supplying electrical power for recreational vehicles. You should
not modify the generator or use it for any application other than
for what it was designed. If there are questions pertaining to
its application, write or call the factory. Do not use the unit until
you have been advised by a competent authority.
installer complied with all applicable codes, standards and reg¬
ulations pertaining to installation.
Owners/Operators should make sure nothing is done during
installation that might render the unit unsafe or in noncompli¬
ance with applicable codes, standards and instructions. They
should be sure the unit has been installed to allow adequate
ventilation for cooling and exhaust air.
DANGER: FOR FIRE SAFETY, THE GENERATOR
MUST HAVE BEEN PROPERLY INSTALLED IN
COMPLIANCE WITH (1) ANS1119.2-1975/NFPA
501C-1974 "STANDARD FOR RECREATIONAL
VEHICLES", PART III, "INSTALLATION OF ELEC¬
TRICAL SYSTEMS." THE GENERATOR ALSO
MUST HAVE BEEN INSTALLED IN STRICT COMPLI¬
ANCE WITH THE MANUFACTURER'S DETAILED
INSTALLATION INSTRUCTIONS. AFTER INSTALLA¬
TION, DO NOTHING THAT MIGHT RENDER THE
UNIT IN NON-COMPLIANCE WITH SUCH CODES,
STANDARDS AND INSTRUCTIONS.
You can use this generator to supply electrical power for oper¬
ating 120/240 volts, single phase, 60 Hertz, AC electrical
loads. These loads can require up to 6600 watts of (6.6 kW)
of power, but cannot exceed 55 AC amperes of current at 120
volts or exceed 27.5 AC amperes at 240 volts.
CAUTION: Do not overload the generator. Some
installations may require that electrical loads be
alternated to avoid overloading. Applying exces¬
sively high electrical loads may damage the
generator and may shorten its life. Add up the
rated watts of all electrical lighting, appliance, tool
and motor loads the generator will power at one
time. This total should not be greater than the
wattage capacity of the generator. If an electrical
device nameplate gives only volts and amps, multi¬
ply volts times amps to obtain watts (volts x amps
= watts). Some electric motors require more watts
of power (or amps of current) for starting than for
continuous operation.
INSTALLATION
This Owner’s Manual has been prepared under the assump¬
tion that a competent, qualified technician installed the
generator into a recreational vehicle. We also assume the
SAFETY
Before using the generator set, carefully read GENERAL
SAFETY RULES inside the cover. Comply with these RULES
to prevent accidents and damage to equipment and/or prop¬
erty. Generac suggests copying and posting the GENERAL
SAFETY RULES in potential hazard areas of the recreational
vehicle. Safety should be stressed to all operators of this
equipment.
GENERATOR AC CONNECTION SYSTEM
This generator set is equipped with dual Stator a-c power
windings. These two stator windings supply electrical power
to customer electrical loads by means of a dual 2-wire con¬
nection system. Note, however, that neutral is grounded.
The generator may have been installed so that units power 120
volts AC loads (Figure 1); or you can wire them to connect both
120 and/or 240 volts AC electrical loads. Be sure to install
jumper wire between the circuit breakers when reconnecting
for 120/240 volts. Refer to the Installation Manual for more infor¬
mation.
Figure 1 — Connections for 120 Volts Only
Recreational Vehicle Generator

■ MAIN BREAKER _
Protects generators AC output circuit against overload and pro¬
vides a method of turning OFF the generators 120/240 volts
AC output to vehicle circuits. The NP-66LPG has one 20 amp
breaker and one 30 amp breaker.
NOTE: If the Series NP-66LPG has been reconnected for dual
voltage AC output (120/240 volts), you can install line break¬
ers having an amperage rating that is different than stated
above. The replacement line breakers consist of two separate
breakers with a connecting piece between the breaker handles
(so that both breakers will operate at the same time). If the unit
is reconnected for dual voltage, it is no longer RVIA listed.
REMOTE START/STOP PANEL
A remote mounted Start/Stop Panel is available, which allows
you to start and stop the generator engine conveniently from
inside the vehicle.
■ FUEL PRIMER _
Before starting a cold engine (it has not been started in more
than two weeks), you must press this switch to bring fuel
from the tank to the fuel regulator. This rocker type switch
springs back into its original position when you release it.
■ START/STOP SWITCH _
To crank and start the engine, hold this switch at its START
position. Release the switch when the engine starts. To stop
an operating engine, press and hold the switch in its STOP
position until the engine shuts off. The switch center position
is the RUN position.
■ FUSE _
Protects the engine DC control circuit against electrical over¬
load. If the fuse element has melted open due to overloading,
the engine cannot be cranked. If you must replace it, use only
an identical replacement fuse.
GENERATOR CONTROL PANEL
Mounted on the generator control panel (Figure 2) are the fol¬
lowing features:
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Generac NP-66LPG Recreational Vehicle Generator
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BEFORE STARTING THE ENGINE
IMPORTANT: INSTRUCTIONS AND INFORMATION IN THIS
MANUAL ASSUME THE GENERATOR HAS BEEN PROP¬
ERLY INSTALLED, CONNECTED, SERVICED, TESTED AND
ADJUSTED BY A QUALIFIED INSTALLATION TECHNICIAN
OF INSTALLATION CONTRACTOR.
■ INSTALLATION _
Generator installation must have been properly completed so
it complies with all applicable codes, standards and regula¬
tions and with the manufacturer's recommendations.
■ ENGINE LUBRICATION _
Have engine crankcase properly serviced with recommended
oil before starting. Refer to “Maintenance" and "Specifica¬
tions* sections for oil servicing procedures and
recommendations.
CAUTION: Any attempt to crank or start the
engine before you have properly serviced it with
the recommended oil may result in engine failure.
■ FUEL SUPPLY _ "
The engine must have adequate supply of proper fuel to oper¬
ate. Before starting, check that sufficient fuel is available.
■ COOLING AND VENTILATING AIR
Air inlet and outlet openings in the generator compartment must
be open and unobstructed for continued proper operation. With¬
out sufficient cooling and ventilating air flow, the
engine-generator quickly overheats, which causes it to quickly
shutdown. Overheating could also damage the unit or your
vehicle.
■ ENGINE EXHAUST GAS _
Before starting the generator engine, you should be sure
there is no way for exhaust gases to enter the vehicle interior
and endangering people or animals. Close windows, doors and
other openings in the vehicle that, if open, might permit exhaust
gases to enter the vehicle.
DANGER: THE GENERATOR ENGINE GIVES OFF
DEADLY CARBON MONOXIDE GAS THROUGH ITS
EXHAUST SYSTEM. THIS DANGEROUS GAS, IF
BREATHED IN SUFFICIENT CONCENTRATIONS,
CAN CAUSE UNCONSCIOUSNESS OR EVEN
DEATH. DO NOT OPERATE THE GENERATOR IF
ITS EXHAUST SYSTEM IS LEAKING OR HAS BEEN
DAMAGED. SYMPTOMS OF CARBON MONOXIDE
POISONING ARE (A) INABILITY TO THINK COHER¬
ENTLY, (B) VOMITING, (C) TWITCHING MUSCLES,
(D) THROBBING TEMPLES, (E) DIZZINESS, (F)
HEADACHE, (G) WEAKNESS AND SLEEPINESS. IF
YOU FEEL ANY OF THESE SYMPTOMS, MOVE
INTO FRESH AIR IMMEDIATELY. IF SYMPTOMS
PERSIST, GET MEDICAL HELP.
STARTING THE GENERATOR
To start the generator from either the generator control panel
or from the optional Remote Panel, proceed as follows:
1. Turn OFF electrical loads, using whatever means provided
in your vehicle (such as a main line circuit breaker or trans¬
fer switch.
NOTE: If starting from the generator panel, turn OFF loads
by setting the generators main circuit breaker to “OFF or
“OPEN". If starting from a Remote Panel, turn OFF loads using
whatever means is provided in the vehicle (such as a main
circuit breaker).
2. Hold the engine Start/Stop Switch at START to crank engine.
Release the switch when the engine starts.
3. Let the engine run at no-load for a few minutes to stabilize
and warm up.
4. Turn ON electrical loads, using whatever means provided
(such as a main circuit breaker or transfer switch).
STOPPING THE GENERATOR
1. T um OFF all electrical loads, using whatever means pro¬
vided (such a main circuit breaker or transfer switch).
2. Place Start/Stop switch in its STOP position.
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Generac NP-66LPG Recreational Vehicle Generator
APPLYING LOADS TO GENERATOR
When applying electrical loads to the generator, observe these
guidelines:
• Before applying electrical loads, let the generator stabilize
and warm up for a minute or two.
• DO NOT overload the generator.
■ LETTING THE ENGINE STABILIZE
The generator supplies correct rated frequency and voltage
only at the proper governed speed. Some electrical appli¬
ances may be extremely sensitive to voltage and frequency.
Incorrect frequencies and/or voltages can damage those appli¬
ances.
If electrical loads are applied at reduced operating speeds, such
loads imposed on the engine when sufficient power is not avail¬
able may shorten engine life. Never turn ON electrical loads
until after the generator engine has started and stabilized
ON-speed.
■ DO NOT OVERLOAD THE GENERATOR
You can read the rated wattage/amperage capacity of your
generator on the generator data plate (see “Identification
Record” on Page 1).
Applying electrical loads in excess of the unit’s rated capac¬
ity will cause the engine-generator to automatically shutdown.
To avoid overloading, add up the wattage of all connected elec¬
trical lighting, appliance, tool and motor loads. This total should
not be greater than the generator’s rated wattage capacity.
• Most lighting, appliance, tool and motor loads indicate their
required watts on their nameplate or data plate. For light
bulbs, simply note the wattage rating of the bulb.
• If a load does not show its rated wattage, multiply that load’s
rated VOLTS times AMPS to obtain WATTS.
• Induction type motors (such as those that run the vehicle’s
furnace fan, refrigerator, air conditioner, etc.) need about 2-
1/2 times more watts of power for starting than for running
(for a few seconds during motor starting). Be sure to allow
for this when connecting electrical loads to the generator.
First, figure the watts needed to start electric motors in the
system. To that figure, add the running wattages of other
items that will be operated by the generator.
• Do not apply heavy electrical loads for the first two or three
hours of operation.
’Air Conditioner (12.000 Btu).
Battery Charger (20 amp).
Belt Sander (3").
Chain Saw......
Circular Saw (6-12").
Coffee Maker.
’Compressor (1 HP).
’Deep Freeze.
Disc Sander (9").
Electric Range (one element)
Electric Skillet.
’Furnace Fan (1/3 HP)..
Hair Dryer...
Hand Drill (1").
Hedge Trimmer.
Impact Wrench..
WATTAGE REFERENCE GUIDE
RUNNING RUNNING
WATTS WATTS
.1700 Lawn Mower.1200
.500 Light Bulb.100
.1000 Microwave Oven. 7 00
.1200 ’Milk Cooler.1100
800 to 1000 Oil Burner on Furnace.300
.1000 Oil Fired Space Heater (140,000 Btu).400
.2000 ’Paint Sprayer, Airless (1/3 HP).600
.500 Radio...50 to 200
.1200 ’Refrigerator..v. 600
.1500 Slow Cooker... 2 00
..1250 ’Submersible Pump (1-1/2 HP)....2800
.1200 ’Submersible Pump (1 HP).:..2000
.1200 *TableSaw (10”) . . 1 7 50 to 2000
.1100 Television....1750 to 2000
.450 ’ Allow 2-1/2 times the listed watts for starting these
.500 devices.
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Generac NP-66LPG Recreational Vehicle Generator
ADDITIONAL INFORMATION
This section discusses some of the engine protective devices,
overload protection and breaking in a new generator.
■ AUTOMATIC LOW OIL PRESSURE
SHUTDOWN _
The engine is equipped with a normally-open (N.O.) oil
pressure switch (Figure 4). Engine oil pressure holds the
switch open during cranking and operation. Should oil pres¬
sure drop below about 8-10 PSI, the switch contacts close
and the engine automatically shuts down.
Figure 4 — Switches for Engine
Safety Shutdown
■ HIGH TEMPERATURE SHUTDOWN
An oil temperature switch (Figure 4) with normally-open (N.O.)
contacts is mounted near the oil filter. If oil temperature were
to exceed about 284°F (140°C), the switch contacts close
and the engine shuts down.
■ FIELD BOOST _
The Controller Circuit Board houses a field boost diode and
resistor which are not part of the automatic choke circuit.
These two components are part of a “field boost" circuit (Figure
5). During engine cranking only, a positive DC (battery) volt¬
age is delivered through the diode, resistor, brushes and slip
rings, and the generator rotor. Application of this voltage to
the rotor Hashes the field" whenever it is started. Hashing of
the field each time the generator starts makes sure that a suf¬
ficiently strong magnetic field is available to produce “pick up"
voltage in the stator windings.
■ OVERVOLTAGE PROTECTION
A solid state voltage regulator (Figure 6) controls the gener¬
ator’s AC output voltage. This regulator supplies an excitation
current to the rotor. By regulating the rotor’s excitation current,
the strength of its magnetic field is regulated and, in turn, the
voltage delivered to connected electrical loads is controlled.
When the AC frequency is 50 Hz, voltage is regulated at 120
volts (voltage-to-f requency ratio is 2-to-1).
Figure 6 — Solid State Voltage Regulator
The voltage regulator also incorporates a “voltage surge pro¬
tection circuit.” This circuit prevents troublesome surges in the
generator AC output voltage. Voltage surge is a common
cause of damage to electronic equipment.
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Generac NP-66LPG Recreational Vehicle Generator
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■ 25-HOUR BREAK IN PERIOD _
The first 25 hours of operation are for “breaking in” the new
generator. Correctly breaking in the generator is essential to
minimize fuel consumption and provide maximum engine per¬
formance. During this 25-hour break in period, comply with the
following:
• Run the unit at varying electrical loads, to help seat engine
piston rings properly.
• For the 75 hours of operation after the “break in” period, avoid
light electrical loads. Load the generator at 50% (or more)
of its rated wattage capacity. Repeated light loads during the
break in period can cause improper seating of engine piston
rings, which could cause blowby and high oil consumption.
• During the break in period, check engine oil level frequently.
It is normal for oil consumption to be high during the break¬
ing in period.
• After the 25-hour break-in period, complete the tasks rec¬
ommended under “25-hour Check Up.”
■ 25-HOUR CHECK UP _ „„
After the 25-hour break-in period, contact an authorized ser¬
vice facility for the following maintenance. The vehicle owner
is responsible for any charges:
• Change engine crankcase oil and oil filter.
• Check ail fluid levels.
• Inspect cooling and ventilation openings on the vehicle.
• Check engine carburetor adjustments.
• Check engine ignition system.
• Inspect entire electrical system.
• Inspect the engine exhaust system.
■ OPERATION IN HIGH GRASS OR
BRUSH
WARNING: NEVER OPERATE THE GENERATOR
WHILE THE VEHICLE IS PARKED IN HIGH GRASS,
WEEDS, BRUSH OR LEAVES. SUCH MATERIALS
CAN IGNITE AND BURN FROM THE HEAT OF THE
EXHAUST SYSTEM. THE GENERATOR EXHAUST
BECOMES EXTREMELY HOT DURING OPERATION
AND REMAINS HOT FOR A LONG TIME AFTER IT
HAS SHUT DOWN.
Recreational Vehicle Generator

Generac NP-66LPG Recreational Vehicle Generator
FUEL REQUIREMENTS
The “NP” series generator is equipped with a liquefied petro¬
leum (LP) gas fuel system. LP gas is usually supplied as a
liquid in pressure tanks.
“NP” series generators require a “vapor withdrawal” type fuel
system. This type of gaseous fuel system uses the vapors form¬
ing above the liquid fuel in the storage tank. Air temperature
around the storage tank must be high enough to sustain ade¬
quate fuel vaporization. In colder climates, you may need to
use an independent heat source to be sure the fuel suffi-
cently vaporizes in the storage tank.
LP gas may consist of propane, butane or mixture of two
gases. Propane vaporizes at temperatures as low as -20° F
(-29°C), but butane returns to its liquid state when the tem-
perture drops below about 32°F (0°C). For that reason, a
higher ratio of propane is desired in the gas mixture when tem¬
peratures drop below freezing.
ENGINE OIL REQUIREMENTS
Use a high quality detergent oil classified “For Service SP and
with an oil viscosity rating of SAE10W-30 oil. Do not pour in
any additives to the recommended oil. Engine crankcase
capacity is 1.5 U.S. quarts (1.4 liters). See MAINTENANCE
section for oil level check and filing procedures.
ENGINE SPECIFICATIONS
Type of Engine.
Cooling Method.
Rated Horsepower.
Displacement.
Compression Ratio.
Cylinder Block.
Type of Governor.
Engine Governed Speed.
Air Cleaner.
Starter.
Ignition System.
Recommended Spark Plugs
Champion.
AC.
Fram Autolite.
Spark Plug Gap.
.Twin Cylinder
.Air-cooled
.,.16 at 3600 rpm
...479.4cc
.8.6 tol
.Aluminum with cast
iron sleeve
....Mechanical, fixed
speed
.See chart above
.Paper element with
foam pre-cleaner
.12 volts DC electric
.Solid state with
flywheel magneto
.RC12YC
..R45S
..65
.0.030 inch (0.8mm)
GENERATOR SPECIFICATIONS
Rotor RPM. 3600
Rotor Poles...’.2
Engine RPM.2700
Rated Maximum Continuous
AC Output.6600 watts (6.6 kw)
Voltage.120 volts*
Rated Maximum Continuous AC Current.55 amperes
Phase.single
Frequency.1.60 Hertz
Weight.213 pounds
Length.25 inches
Width.18.5 inches
Height.15.75 inches
* The unit is reconnectable to 120 and/or 240 volts, dual voltage
output.
Rated maximum continous current at 240 volts is 27.5 amps.
Recreational Vehicle Generalor
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Generac NP-66LPG Recreational Vehicle Generator
This section includes information about simple maintenance
which includes the following tasks:
• Checking engine oil level.
• Changing engine oil.
• Changing oil filter.
• Changing the air cleaner.
• Cleaning the air intake screen.
• Cleaning spark plugs.
CHECKING ENGINE OIL LEVEL
Check engine crankcase oil level at least every eight hours of
operation, or before each use (Figure 7).
• Be sure the generator is as level as possible.
• Remove oil dipstick and wipe dry with clean, lint-free cloth.
• Install and tighten oil dipstick, then remove again.
• Oil should be at dipstick FULL mark. If necessary,,add the
recommended oil to the FULL mark only. DO NOT FILL
ABOVE “FULL” MARK.
• Install and tighten oil dipstick cap before operating the
engine.-
NOTE: See “Engine Oil Requirements" on Page 12 for rec¬
ommended oils.
Figure 7 — Oil Dipstick and Fill Tube
CHANGE ENGINE OIL
Change engine oil after the first 25 hours of operation (after
the 25 hour break-in period, Page 8). Thereafter, change oil
every 50 operating hours. Change oil more frequently if oper¬
ating consistently under heavy load or at high ambient
temperatures.
• Warm up engine for at-leastfive minutes, then shut down.
' -
• With engine still warm from running, remove cap from oil
drain hose (Figure 8). Drain oil completely into a suitable
container.
• When oil has drained, install and tighten drain hose cap.
• Remove oil dipstick and fill crankcase with the recom¬
mended oil (See Page 12). The engine crankcase can hold
about 1.4 liters. DO NOT FILL ABOVE “FULL” MARK.
• Install and tighten dipstick cap before operating engine.
CHANGE OIL FILTER
Replace the engine oil filter after the first 25 hours of opera¬
tion, every 100 operating hours thereafter.
• Turn oil filter counterclockwise to remove (Figure 9).
• Coat gasket of new filter with engine oil.
• Turn new filter clockwise until its gasket contacts tightly with
the filter adapter. Then tighten with an additional 3/4 to one
turn by hand.
• Run engine,and check for leaks.
NOTE: Check oil level and fill to full mark after checking for
leaks. Filter will retain some oil.
Recreational Vehicle Generator
13

Generac NP-66LPG Recreational Vehicte Generator
ENGINE AIR CLEANER
Clean and re-oil the foam pre-cleaner every three months or
ever 25 hours of operation, whichever occurs first. Service
the foam pre-cleaner more frequently if you operate the gen¬
erator in extremely dusty or dirty conditions (Figure 10):
• Turn KNOB counterclockwise to loosen.
• Remove COVER, FOAM PRE-CLEANER and PAPER
FILTER.
• Remove foam pre-cleaner from cover
• Wash foam pre-cleaner in liquid detergent and water.
• Wrap foam pre-cleaner in a cloth and squeeze dry.
• Saturate foam pre-deaner in engine oil. Squeeze to remove
excess oil and to distribute oil.
• Install foam pre-cleaner into cover, followed by paper filter.
Tabs at edges of paper filter must lock into slots on cover.
Once each year or every 100 operating hours (whichever
comes first), replace the paper filter. The new replacement
filter must be a flame retardent type.
CLEAN AIR INTAKE SCREEN
Clean all foreign material from the air intake screen (Figure
11) at lease once every 100 hours of operation. Clean more
often if necessary. *
Inspect the area around the generator exhaust muffler peri¬
odically and remove all grass, leaves, dirt, etc. from this area.
Figure 11 — Cleaning Air Intake Screen

MISCELLANEOUS MAINTENANCE
■ SPARK ARRESTOR MUFFLER
If the generator is not equipped with a spark arrestor exhaust
muffler and is to be used on any forest covered, brush cov¬
ered or grass covered unimproved land, you may have to
install a spark arrestor. The spark arrestor must be maintained
in effective working order by the vehicle owner/operator.
For assistance in ordering, installing and maintaining spark
arrestor exhaust mufflers, contact your nearest authorized
service facility.
Exhaust mufflers supplied by Generac are spark arrestor
types. Generac exhaust mufflers for recreational vehicle gen¬
erators do not have a spark arrestor screen, but are of the more
efficient “toriod" or “swirl" type. To remove carbon and com¬
bustion deposits from such mufflers, remove the PLUG from
muffler and run engine for about 15 minutes. Shut engine.down,
let the muffler cool and install the plug.
WARNING: BE SURE TO RE-INSTALL THE PLUG
FROM THE MUFFLER TIGHTLY. ENGINE VIBRATION
COULD CAUSE A LOOSE PLUG TO FALL OUT.
WITHOUT THE PLUG IN PLACE, HOT ENGINE
EXHAUST IS DIRECTED OUT THE OPENING. THIS
HOT EXHAUST, DEPENDING ON THE INSTALLA¬
TION, COULD BE DIRECTED TO AREAS NOT ABLE
TO WITHSTAND THE EXTREME HEAT SUCH AS
WOODEN FLOOR BOARDS OR OTHER FLAMMA¬
BLE MATERIAL THIS COULD RESULT IN A FIRE.
■ BATTERY
All lead-acid storage batteries will discharge when not infuse.
Inspect the generator battery as follows: ’ .'£>
Once Weekly
Inspect battery posts and cables for tightness, corrosion. Clean
and/or tighten as necessary.
Also check battery fluid level, and, if necessary, fill with DIS¬
TILLED WATER ONLY. DO NOT USE TAP WATER IN
BATTERY.
Every Six Months
Have the battery state of charge and condition checked by an
automotive service facility. This should be done with an auto¬
motive type battery hydrometer.
DANGER: STORAGE BATTERIES GIVE OFF
EXPLOSIVE HYDROGEN GAS. THIS GAS CAN
FORM AN EXPLOSIVE MIXTURE AROUND THE
BATTERY FOR SEVERAL HOURS AFTER CHARG¬
ING. THE SLIGHTEST SPARK CAN IGNITE THE GAS
AND CAUSE AN EXPLOSION. SUCH AN EXPLO¬
SION CAN SHATTER THE BATTERY AND CAUSE
BLINDNESS OR OTHER INJURY. ANY AREA THAT
HOUSES A STORAGE BATTERY MUST BE PROP¬
ERLY VENTILATED. DO NOT ALLOW SMOKING,
OPEN FLAME, SPARKS OR ANY SPARK PRODUC¬
ING TOOLS OR EQUIPMENT NEAR THE BATTERY.
■ CLEANING THE GENERATOR _
Keep your generator set as demand dry as possible. Dirt and mois¬
ture that are permitted to accumulate on electrical windings have
an adverse affect on the insulation resistance of these wincfi ngs.
Moisture that is allowed to remain in contact with windings will
be retained in voids and cracks of the windings. Dirt makes
the problem worse, since it tends to hold the moisture into con¬
tact with the windings. Salt, as from sea air, worsens the
problem since it tends to absorb moisture from the air. The com¬
bination of salt and moisture makes a good electrical conductor.
CAUTION! Do NOT use a forceful spray of water to
clean the generator. Water will enter the generator
Interior and cause problems, and may also conta¬
minate the generator fuel system.
-DANGER: BATTERY ELECTROLYTE FLUID
IS AN EXTREMELY CAUSTIC SULFURIC ACID
_SOLUTION THAT CAN CAUSE SEVERE BURNS.
DO NOT PERMIT FLUID TO CONTACT EYES, SKIN,
CLOTHING, PAINTED SURFACES, ETC. WEAR
PROTECTIVE GOGGLES, PROTECTIVE CLOTHING
AND GLOVES WHEN HANDLING A BATTERY. IF
YOU SPILL THE FLUID, FLUSH THE AFFECTED
AREA IMMEDIATELY WITH CLEAR WATER.
DANGER: DO NOT USE ANY JUMPER CABLES OR
BOOSTER BATTERY TO CRANK AND START THE
GENERATOR ENGINE. IF ANY BATTERY HAS DIS¬
CHARGED, REMOVE IT FROM THE VEHICLE FOR
RECHARGING.
Recreational Vehicle Generator
15

■ MAJOR SERVICE MANUAL _
To obtain a service manual for your generator, order it from
your dealer/distributor or contact the factory. Be sure to iden¬
tify your unit’s MODEL NUMBER and SERIES.
■ DRIVE BELTS _
The engine drives the generator rotor by means of a pulley
and drive belt arrangement. The drive train, drive belt and pul¬
leys are warranted for the life of the generator. Drive belt
tension was properly adjusted before the unit was shipped from
the factory. If you suspect that drive belt tension is incorrect,
contact an authorized service facility.
OUT OF SERVICE PROTECTION
If you cannot exercise the generator every seven days and it
is to be out of service longer than 30 days, prepare the gen¬
erator for storage as follows:
• Start the engine and let it warm up.
• Close the fuel shutoff valve in the fuel supply line and let
the engine “run out of fuel."
• While the engine is still warm from running, drain the oil com¬
pletely. Refill the crankcase with SAE10W-30 oil having an
API classification “For Service SR”
• Attach a tag to the engine indicating the viscosity and clas¬
sification of the oil in the crankcase.
• Remove spark plugs and pour about two or three table¬
spoons of clean, fresh engine oil into spark plug threaded
openings. Crank engine several times to distribute oil, then
install and tighten spark plugs. ,
• Remove the battery and store in a cool, dry room on a
wooden board. Never store the battery on any concrete or
wooden floor.
• Clean and wipe the entire generator.
RETURN THE UNIT TO SERVICE
AFTER STORAGE
To return the unit to service after storage, proceed as follows:
• Check tag on engine for oil viscosity and classification.
Verify that the correct recommended oil is used in the
engine. If necessary, drain and refill with proper oil.
• Check battery. Fill all cells to the proper level with distilled
water. DO NOT USE TAP WATER IN THE BATTERY.
Recharge battery to 100% state-of-charge, or, if defective,
replace the battery.
• Turn OFF all electrical loads, then start the engine.
• Let the engine warm up.
• Apply electrical loads to at least 50% of the unit’s rated
wattage capacity.
• When the engine is thoroughly warmed, shut it down.
THE GENERATOR IS NOW READY FOR SERVICE.
Recreational Vehicle Generator

TROUBLESHOOTING POINTS
PROBLEM CAUSE CORRECTION
Engine won’t crank. 1. 15 amp fuse blown. 1. Replace fuse.
2. Loose or corroded or defective 2. Tighten, dean or replace
battery cables as necessary.
3. Defective starter contactor. 3. Replace contactor.
4. Defective starter motor. 4 Replace starter motor.
5. Battery is discharged or defective. 5. Recharge or replace battery.
6. Defective Controller Circuit Board 6. Replace defective circuit board.
Engine cranks but wont start
Engine starts hard, runs rough.
Engine starts, shuts down when
Start/Stop switch is released.
No AC output from generator.
1. Out of fuel.
2. Fuel shutoff valve to RV fuel system
(if so equipped) is closed.
3. Engine is flooded.
4. Defective Controller Circuit Board
5. Spark plugs defective.
6. Defective ignition magneto on engine.
7. Bad carburetor.
8. Dirty engine air cleaner filter.
1. Dirty engine air cleaner filter.
2. Defective spark plugs.
3. Defective ignition magneto on engine.
1. Engine oil level is low.
2. Defective Controller Circuit Board.
3. Defective Low Oil Pressure Switch
4. Loss of generator AC-output.
1. Check main line circuit breaker.
2. Transfer switch (if so equipped) is set
to wrong position.
3. Failure in vehicle electrical system.
4. Generator component failure.
1. Replenish fuel tank.
2. Open fuel shutoff valve.
3. Wait 5-10 minutes; try again.
4. Replace defective circuit board.
5. Clean, regap or replace plugs.
6. Replace, if defective.
7. Adjust, repair or replace.
8. Clean or replace filter as needed.
1. Clean or replace filter as needed.
2. Clean, regap or replace plugs.
3. Replace, if defective.
1. Check oil and add oil as needed.
2. Replace if defective.
3. Replace defective switch.
4. Contact an authorized service
facility.
1. Reset to ON or CLOSED.
2. Reset transfer switch.
3. See vehicle manual.
4. Contact an authorized service
facility.
Recreational Vehicle Generator

O* Generac NP-66LPG Recreational Vehicle Generator
V //.Vi*. t ■ .?'
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Drawing No. 95956
EXPLODED VIEW - BASE AND PULLEYS

Drawing No. 95956
Generac NP-66LPG Recreational Vehicle Generator
REPAIR PARTS - BASE AND PULLEYS
ITEM PART NO
QTY.
DESCRIPTION
1
86318
1
Mounting Base
2
90141 1
Ground Catte
3 46911
4 Rubber Mount
4 25017
8
3/8"-16x 1/2" Capscrew
5
46526 10
Ml 0 Lock Washer
6 22129
2
M8 Lock Washer
7
72391
2 Rubber Mount Skid
8 77603
2
51/6M8X 3-1/2* Bolt
9 22259
2
5/16-18 Hex Nut
10 52858
6
M8-1.25 Flanged Lock Nut
11
51730
2
M8-1.25 x 60mm Capscrew
12
29459
2
Belt Tension Spring
13 75215
2
Spring Center Washer
14
73146
4
Nylon Slide
15
75209 2
Nylon Slide Support
16
73174
1
Exhaust Manifold
17
79678 2
Exhaust Manifold Gasket
18 55173 4
M8-1.25 x 20mm Capscrew
19
72383
2 Collector Pan Gasket
20
90859 1
Cover Plate A External
21
75224F 1 Engine Pulley
22
73106F
1 Alternator Pulley
23
75216 1 40" Poly Vinyl 4L Belt
24
49451
1
Pulley Retainer Washer
25
42633 1
3/8"-24 x 1* Capscrew
26 . 77017
1
Blower Housing Guide
27 73118 1
3/8*-24 x 2-1 /2“ Capscrew
28
74906
5
M6-1.00 x 20mm Screw
29 23152 '
4
3/8“-16 x 3/4* Capscrew
30
72375
1
Biower Housing
31
73185 1
Blower Housing Spacer
32 22097 6 M6 Lock Washer
33
77682 1 M5-0.8 x 80mm Capscrew
34
75242 4 Generator Mounting Spring
35 49813 2
M6-1.00HexNut
36
45757
2 M6-1.0 x 25mm Capscrew
42
26925
1 3/8" NPT Oil Drain
43
7571OA 1
OH Fill and Drain Tube
44
74958
1
Cap and Dipstick Assembly
45
67871
1 O-ring Cap
-46 75712' -
1
O-ring Drain
ITEM PART NO. QTY.
DESCRIPTION
47 75711 1 O-ring Adaptor
56 73179
1
Off Filter Support
57
70185
1 Oil Filter
58 60108
1
Oil Pressure Switch
59 74948 3
5/16* Fitting
60 74950
1
Outer Oil Tube
61 74951
1
Inner Oil Tube
62 73134
1
Oil Pad Adaptor
63 38750
3
M6-1.00 x 30mm Capscrew
64 74949
1
5/16'90-degree Fitting
65
68548
1
Oil Pad Gasket
66
62684 1 Grounding Lug
67
29289
A
1/16’ x & Foam Tape
69
75281
1
High Temperature Switch
70
74027 2
M3-0.5 Pan Head Screw
71 43182
2
M3 Lock Washer
73
75237 4
Spring Retainer Washer
74
77681
1
LOS 2-wire Vinyl Cap
75
75474
1
17* x 42“ x 2* Vinyl Cap
76
90800 1
Exhaust Elbow
77
74907
1
1-1/8’Exhaust Clamp
78
75226
1
Air Cover
79 56893 14
#10-24x1/2“ Screw
80
75229
1
Slide Pan Gasket
81
75227 1 Slide Pan
82
79246
4
M6-1.0x 16mm Capscrew
with lock washer
83
22473
4
M6 Rat Washer
85
72384C
1
Exhaust Outlet Cover
87
77643
2
Exhaust Outlet Gasket
90
22447 1
M6 Toothed Lock Washer
91 90088
1 Vinyl coated Clamp
92-
74908
10
M5-0.8 x 10mm Screw
93 81105
2
5/16'-18 Flange Nut (special)
94
23897 6
M5 Rat Washer
95 67210
1
Decal A Ground
96 45756
4
M6 x 10mm Taptite Screw
97
22131
1
Ml 0 Rat Washer
98
68527 4
M6-1.0 x 20mm Capscrew with
Lockwasher
Recreational Vehicle Generator