Spectrum 3.0L GM Quick start guide

2011 Emission Certified
LPG Fuel System
3.0L GM Engine
Parts & Service Manual
Including Labor Time Guide
Revision A/March, 2011

2011 Emission Certified
LPG Fuel System
3.0L GM Engine for
Parts & Service Manual
Table of Contents
General Information................................................................................................5
An overview of this Service Manual
Maintenance............................................................................................................9
General maintenance and maintenance interval information
Fuel System...........................................................................................................17
An overview of the LPG fuel system and its components
LPG Fuel System Diagnosis ................................................................................27
How to identify a general problem
LPG Symptom Diagnostics..................................................................................35
How to correct a specific problem
Electrical Section..................................................................................................51
Diagnostic Scan Tool......................................................................................53
Using the DST for testing and trouble shooting

Wire Schematic...................................................................................................81
Engine wiring schematics
Engine Wire Harness Repair .............................................................................85
Repairing a wire harness on the vehicle
Diagnostic Trouble Codes (DTCs) ....................................................................89
Application, schematic and DTC specific code information
Servicing the Fuel System.................................................................................... 237
Step by step instructions on how repair and/or replace fuel related Components
LPG Parts Diagram................................................................................................ 255
Illustrations and part views
Labor Time Guide .................................................................................................. 299
The labor reimbursed by IMPCO for warrantable service and repairs
Definitions .............................................................................................................. 317
Definitions of phrases and acronyms used throughout this Service Manual
Appendix ................................................................................................................ 323
Supplemental charts and tables

4

5
General Information

6
INTRODUCTION
This service manual supplement has been devel-
oped to provide the service technician with the
basic understanding of the IMPCO certified fuel
and emission systems for the 3.0L GM engine.
This manual should be used in conjunction with
the base engine manual and the OEM service
manual when diagnosing fuel or electrical prob-
lems.
HOW TO IDENTIFY THE ENGINE YEAR
The emission label on the engine will identify the
specific model year.
SERVICING YOUR EMISSIONS
CERTIFIED ENGINE
Any maintenance and repair should be performed
by trained and experienced service technicians.
Proper tools and equipment should be used to
prevent injury to the servicing technician and
damage to the vehicle or components. Service
repairs should always be performed in a safe envi-
ronment and the technician should always wear
protective clothing to prevent injury.
For parts or labor to be reimbursed under the
IMPCO Technologies Inc. emission warranty, only
work performed by IMPCO or OEM trained techni-
cians using only IMPCO specified parts will qualify
for reimbursement. Refer to the IMPCO Labor
Time Guide for additional information.
For parts or labor not reimbursed under warranty,
a repair shop or person of the owner’s choosing
may maintain, replace, or repair emission-control
devices and systems. It is highly recommended
that any replacement parts used for maintenance
or for the repair of emission control systems be
new OEM replacement parts. The use of other
than genuine IMPCO replacement parts may im-
pair the effectiveness of emission control systems,
therefore, the owner should assure that such parts
are warranted by their manufacturer to be equiva-
lent to genuine IMPCO OEM parts in performance
and durability.
FUEL QUALITY
LPG engines and fuel systems are designed to
operate on HD-5 or HD-10 specification LPG fuel.
Fuel other than HD-5 or HD-10 may cause harm
to the engine’s emission control system and a
warranty claim may be denied on this basis if op-
erators can readily find the proper fuel.* Use of
any other fuel may result in your engine no longer
operating in compliance with CARB or EPA emis-
sions requirements.
*Not Applicable in the state of California.
FUEL LINE CONNECTIONS
Loctite® 567 is recommended for all NPT connec-
tions.
Do not use Teflon tape to seal any fuel fit-
tings. Fragments of the tape may enter into
the fuel system, causing damage or mal-
function of critical fuel system components.
AIR FILTRATION REQUIREMENTS
Dry filtration is required with maximum recom-
mended 4” W.C. restriction @ 75 cfm. IMPCO
strongly recommends the use of OEM or factory
replacement parts.
WASHING
Caution should be used when pressure washing
near or on an engine’s electrical system. Avoid
direct pressure spray on the system electrical
connectors. The electrical connectors are splash
resistant, but if high pressure water or steam is
sprayed directly at the connectors, moisture can
become trapped behind the connector seal and
cause serious system problems, many of them
showing up as intermittent.

7
FUEL SYSTEM CAUTIONS
Do not use Teflon tape to seal any fuel
fittings. Fragments of the tape may en-
ter into the fuel system, causing
damage or malfunction of critical fuel
system components.
Do not smoke, carry lighted tobacco or
use a lighted flame of any type when
working on or near any fuel related
component. Highly flammable air-fuel
mixtures may be present and can be
ignited causing personal injury.
Do not allow LPG to contact the skin.
LPG is stored in the fuel tank as a liq-
uid. When LPG contacts the
atmosphere, it immediately expands in-
to a gas, resulting in a refrigeration
effect that can cause severe burns to
the skin.
Do not allow LPG to accumulate in
areas below ground level such as in a
service pit or underground ventilation
systems. LPG is heavier than air and
can displace oxygen, creating a dan-
gerous condition.
Do not make repairs to the fuel system
if you are not familiar with or trained to
service Propane fuel systems. Contact
the dealer who sold you the engine to
locate a repair facility with trained
technicians to repair your fuel system.
Unlike gasoline or propane vapors that
sink downward. Highly flammable
air/fuel mixtures may be present and
can be ignited causing personal injury.
Always work in well ventilated areas.
WARNINGS, CAUTIONS AND NOTES
This manual contains several different Warnings,
Cautions, and Notes that must be observed to
prevent personal injury and or damage to the en-
gine, the fuel system or personal property.
A “WARNING“ is an advisement that by perform-
ing a process or procedure listed in this manual
improperly may result in serious bodily injury,
death and/or serious damage to the engine or
property.
Typical Warning Label:
A “WARNING” is an advisement that
by performing a process or procedure
listed in this manual improperly may
result in serious bodily injury, death
and/or serious damage to the engine
or property.
A “CAUTION” label or statement is used when it
has been determine that by performing a process
or procedure defined in the manual improperly a
less severe result may occur. It could however,
result in serious bodily injury, and or serious dam-
age to the engine or property damage.
Less severe than WARNING but has
the potential to cause injury or dam-
age. Also used to notify of situations
that could lead to eventual failure, in-
jury or damage.
This caution label may also appear in area of this
manual that applies to service and repair proce-

8
dures. In addition it may also be used to indicate
a failure to observe which may influence the terms
of the warranty.
An “IMPORTANT” statement generally denotes a
situation that requires strict adherence to the as-
sembly, tightening, or service procedure. Failure
to observe this procedure could result in an un-
safe condition or improper performance of the
engine or a component.
A “NOTE” statement applies to a specific item or
procedure that is to be followed during the servic-
ing of the engine or its components.
PROPER USE OF THIS SERVICE MANUAL,
TOOLS AND EQUIPMENT
To reduce the potential for injury to the technician
or others and to reduce damage to the engine dur-
ing service repairs the technician should observe
the following Steps:
The service procedures defined in this ma-
nual, when followed, have been found to be a
safe and efficient process to repair the fuel
system. In some cases special tools may be
required to perform the necessary procedures
to safely remove and replace a failed compo-
nent.
Tools identified in this manual with the prefix
“J” or “BT” can be procured through SPX in
Warren, Michigan.
IMPCO tools identified in this manual with a
prefix “ITK” can be acquired through OEM
Parts Distribution.
IMPORTANT
It is important to remember that there may be a
combination of Metric and Imperial fasteners used
in the installation of the IMPCO fuel system.
Check to insure proper fit when using a socket or
wrench on any fastener to prevent damage to the
component being removed or injury from “slipping
off” the fastener.
The fuel system utilizes fuel lines and hoses with
high pressure connectors. Always use a wrench
of the proper size and torque to the correct value.
For hoses with swivel fittings, be sure not to turn
the fixed fitting which may cause a twisting or
kinking of the hose, possibly resulting in fuel line
restriction and/or leak.
Always leak check any fuel system con-
nection after servicing! Use an
electronic leak detector and/or a liquid
leak detection solution. Failure to leak
check could result in serious bodily in-
jury, death, or serious property damage.

9
Maintenance

10
MAINTENANCE
The maintenance of an engine and related com-
ponents are critical to its operating performance
and lifespan. Industrial engines operate in envi-
ronments that often include hot and cold
temperatures and extreme dust. The recom-
mended maintenance schedule is listed in this
section, however, environmental operating condi-
tions and additional installed equipment may
require more frequent inspection and servicing.
The owner and/or service agent should review the
operating conditions of the equipment to deter-
mine the inspection and maintenance intervals.
When performing maintenance on the engine,
turn the ignition OFF and disconnect the bat-
tery negative cable to avoid injury or damage
to the engine.
ENGINE BELTS
The engine installed in this equipment uses a ser-
pentine drive belt configuration that drives the
water pump, alternator and additional pumps or
devices. It is important to note that the drive belt
is an integral part of the cooling and charging sys-
tem and should be inspected according to the
maintenance schedule in this section. When in-
specting the belts check for:
Cracks
Chunking of the belt
Splits
Material hanging loose from the belt
Glazing, hardening
If any of these conditions exist the belt should be
replaced with the recommended OEM replace-
ment belt.
Alcohol or Methanol based anti-freeze or
plain water are not recommended for use in
the cooling system at anytime.
SERPENTINE BELT SYSTEM
Serpentine belts utilize a spring-loaded tensioner
to keep the belt properly adjusted. Serpentine
belts should be checked according to the main-
tenance schedule in this section.
IMPORTANT:
The use of “belt dressing” or “anti-slipping
agents” on belts is not recommended.
COOLING SYSTEM
It is important that the cooling system of the en-
gine be maintained properly to ensure proper
performance and longevity.
Alcohol or Methanol based anti-freeze or
plain water are not recommended for use
in the cooling system at anytime.
Do not remove the cooling system pres-
sure cap (radiator cap) when the engine is
hot. Allow the engine to cool and then
remove the cap slowly to allow pressure
to vent. Hot coolant under pressure may
discharge violently.
NOTE that the LPG vaporizer is connected to the
cooling system and the fuel system may be ad-
versely affected by low coolant levels and
restricted or plugged radiator cores. Therefore,
the cooling system must be maintained according
to the recommend maintenance schedule in this
section and also include:
The regular removal of dust, dirt and debris
from the radiator core and fan shroud.
Inspection of coolant hoses and components
for leaks, especially at the radiator hose con-
nections. Tighten hose clamps if necessary.
Check radiator hoses for swelling, separation,
hardening, cracks or any type of deterioration.

11
If any of these conditions exist the hose
should be replaced with a recommended OEM
replacement part.
Inspect the radiator cap to ensure proper seal-
ing.
COOLANT
Check coolant level in coolant recovery tank and
add coolant as required. Add 50/50 mixture of
GM Dexcool antifreeze and water or coolant per
engine manufacturer’s instructions. Do not add
plain water. Replace coolant per the recommend-
ed schedule.
IMPORTANT:
The manufacturers of the engine and fuel system
do not recommend the use of “stop leak” additives
to repair leaks in the cooling system. If leaks are
present the radiator should be removed and re-
paired or replaced.
ENGINE ELECTRICAL SYSTEM MAINTNANCE
The engine’s electrical system incorporates com-
puters to control various related components. The
electrical system connections and ground circuits
require good connections. Follow the recom-
mended maintenance schedule in this section to
maintain optimum performance. When inspecting
the electrical system check the following:
Check Positive and Negative cables for corro-
sion, rubbing, chafing, burning and to ensure
tight connections at both ends.
Check battery for cracks or damage to the
case and replace if necessary.
Inspect engine wire harness for rubbing, chaf-
ing, pinching, burning, and cracks or breaks in
the wiring.
Verify that engine harness connectors are cor-
rectly locked in by pushing in and then pulling
the connector halves outward.
Inspect ignition coil wire for hardening, crack-
ing, arcing, chafing, burning, separation, split
boot covers.
Check spark plug wires for hardening, crack-
ing, chafing, arcing or burning, separation, and
split boot covers.
Replace spark plugs at the required intervals
per the recommended maintenance schedule.
Verify that all electrical components are se-
curely mounted to the engine or chassis.
Verify that any additional electrical services
installed by the owner are properly installed in
the system.
Verify that the MIL, charging, and oil pressure
lights illuminate momentarily during engine start.
ENGINE CRANKCASE OIL
OIL RECOMMENDATION
Select an engine oil viscosity that will best match
the prevailing daytime temperature:
The oil must meet GM specification 9986231. Mo-
tor oils meeting this spec receive the API
(American Petroleum Institute) starburst symbol:
ILSAC GF-4 oils are highly recommended. Oils
meeting the SL-4 spec are improved over the pre-
vious generation GF-3 oils in many ways
Reduced Phosphorous levels (20%) for re-
duced catalyst poisoning
Improved oxidation resistance (4X oxidation
inhibitor treat level = 100% improvement)

12
Improved hi temp deposit control (1.5X deter-
gents = 25% improvement)
It is noted that the GF-4 oils are also “backward
compatible” and are equal or better than previous
grades of oil in all aspects.
OEM’s may opt for higher viscosity oils based on
their application experience however GF-4 oils
may not be available in these viscosity ranges. In
this case it is recommended the OEM utilize high
quality oil (API rating SM).
CAUTION: Do not to operate your engine with an
oil level below the normal operating range. Se-
vere engine damage could occur.
SYNTHETIC OILS
Synthetic oils have been available for use in in-
dustrial engines for a relatively long period of
time and may offer advantages in cold and hot
temperatures. However, it is not known if syn-
thetic oils provide operational or economic
benefits over conventional petroleum-based oils
in industrial engines. Use of synthetic oils does
not permit the extension of oil change intervals.
CHECKING/FILLING ENGINE OIL LEVEL
IMPORTANT:
Care must be taken when checking engine oil lev-
el. Oil level must be maintained between the
“ADD” mark and the “FULL” mark on the dipstick.
To ensure that you are not getting a false reading,
make sure the following steps are taken before
checking the oil level.
1. Stop engine.
2. Allow approximately five minutes for the oil to
drain back into the oil pan.
3. Remove the dipstick. Wipe with a clean cloth
or paper towel and reinstall. Push the dipstick
all the way into the dipstick tube.
4. Remove the dipstick and note the amount of
oil on the dipstick. The oil level must be be-
tween the “FULL” and “ADD” marks.
Engine Oil Dip Stick (Typical)
5. If the oil level is below the “ADD” mark reinstall
the dipstick into the dipstick tube and proceed
to Step 6.
6. Remove the oil filler cap from the valve cover.
7. Add the required amount of oil to bring the
level up to, but not over, the “FULL” mark on
the dipstick. Reinstall the oil filler cap to the
valve rocker arm cover and wipe any excess
oil clean.
CHANGING THE ENGINE OIL
IMPORTANT:
When changing the oil, always change the oil
filter.
1. Start the engine and run until it reaches nor-
mal operating temperature.
An overfilled crankcase (oil level being too
high) can cause an oil leak, a fluctuation
or drop in oil pressure. When overfilled,
the engine crankshafts splash and agitate
the oil, causing it to aerate or foam.
IMPORTANT:
Change oil when engine is warm and the old oil
flows more freely.
2. Stop engine

13
Engine oil will be hot. Use protective
gloves to prevent burns. Engine oil con-
tains chemicals which may be harmful to
your health. Avoid skin contact.
3. Remove drain plug and allow the oil to drain.
4. Remove and discard oil filter and its sealing
ring.
5. Coat sealing ring on the new filter with clean
engine oil, wipe the sealing surface on the filter
mounting surface to remove any dust, dirt or
debris. Tighten filter securely (follow filter man-
ufacturer’s instructions). Do not over tighten.
6. Check sealing ring on drain plug for any dam-
age, replace if necessary, wipe plug with clean
rag, wipe pan sealing surface with clean rag
and re-install plug into the pan. Tighten to the
OEM specification.
7. Fill crankcase with oil.
8. Start engine and check for oil leaks.
9. Dispose of oil and filter in a safe and respon-
sible manner.
FUEL SYSTEM INSPECTION AND
MAINTENANCE
LPG FUEL SYSTEM
The LPG fuel system installed on this industrial
engine has been designed to meet the emission
standard applicable for the 2011 model year. To
ensure compliance to these standards, follow the
recommended maintenance schedule contained in
this section.
INSPECTION AND MAINTENANCE OF THE
FUEL STORAGE CYLINDER
The fuel storage cylinder should be inspected
daily or at the beginning of each operational shift
for any leaks, external damage, adequate fuel
supply and to ensure the manual service valve is
open. Fuel storage cylinders should always be
securely mounted, inspect the securing straps or
retaining devices for damage ensure that all lock-
ing devices are closed and locked. Check to
ensure that the fuel storage cylinder is positioned
with the locating pin in the tank collar on all hori-
zontally mounted cylinders this will ensure the
proper function of the cylinder relief valve.
When refueling or exchanging the fuel cylinder,
check the quick fill valve for thread damage. Also
verify O-ring is in place and inspect for cracks,
chunking or separation. If damage to the o-ring
is found, replace prior to filling. Check the ser-
vice line quick coupler for any thread damage.
IMPORTANT:
When refueling the fuel cylinder, wipe both the
female and male connection with a clean rag prior
to filling to prevent dust, dirt and debris from being
introduced to the fuel cylinder.
INSPECTION OF THE FUEL FILTER
The LPG system on this emission certified engine
utilizes an in-line replaceable fuel filter element.
This element should be replaced, at the intervals
specified in the recommended maintenance sche-
dule. When inspecting the fuel filter check the
following:
Check for leaks at the inlet and outlet fittings,
using a soapy solution or an electronic leak
detector and repair if necessary.
Check to make sure filter is securely mounted.
Check filter housing for external damage or
distortion. If damaged replace fuel filter.
AIR FUEL MIXER/THROTTLE CONTROL
DEVICE MAINTENANCE AND INSPECTION
IMPORTANT:
The Air Fuel Mixer components have been
specifically designed and calibrated to meet the
fuel system requirements of the emission certified
engine. The mixer should not be disassembled or
rebuilt. If the mixer fails to operate or develops a
leak the mixer should be replaced with the OEM
recommended replacement parts.
When inspecting the mixer check for the following
items:
Leaks at the inlet fitting.
Fuel inlet hose for cracking, splitting or chaff-
ing, replace if any of these condition exist.
Ensure the mixer is securely mounted.
Inspect air inlet hose connection and clamp.
Also inspect inlet hose for cracking, splitting or
chafing. Replace if any of these conditions ex-
ist.

14
Inspect Air cleaner element according to the
Recommended Maintenance Schedule found
in this section.
Check Fuel lines for cracking, splitting or chaf-
ing. Replace if any of these conditions exist.
Verify Throttle body return action to ensure
throttle shaft is not sticking. Repair if neces-
sary.
Check for leaks at the throttle body and intake
manifold.
PRESSURE REGULATOR MAINTENANCE AND
INSPECTION
IMPORTANT:
The Pressure Regulator components have been
specifically designed and calibrated to meet the
fuel system requirements of the emission certified
engine.
If the Regulator fails to operate or develops a
leak, it should be repaired or replaced with the
OEM recommended replacement parts. When
inspecting the regulator check for the following
items:
Check for any fuel leaks at the inlet and outlet
fittings.
Check for any fuel leaks in the regulator body.
Check the inlet and outlet fittings of the coo-
lant supply lines for water leaks.
Check the coolant supply lines for hardening,
cracking, chafing or splits. If any of these con-
ditions exist replace coolant lines.
Check coolant supply hose clamp connec-
tions, ensure they are tight.
Check to ensure the Regulator is securely
mounted and the mounting bolts are tight.
Check the Regulator for external damage.
Check the Regulator electrical connections to
ensure the connector is seated and locked.
EXHAUST SYSTEM AND CATALYTIC
CONVERTER INSPECTION AND
MAINTENANCE
IMPORTANT:
The exhaust system on this emission certified en-
gine contains Heated Exhaust Gas Oxygen
Sensors (HEGOs) which provide feedback to the
ECM on the amount of oxygen present in the ex-
haust stream after combustion.
The measurement of oxygen in the exhaust
stream is measured in voltage and sent to the
ECM. The ECM then makes corrections to the
fuel air ratio to ensure the proper fuel charge and
optimum catalytic performance. Therefore, it is
important that the exhaust connections remain
secured and air tight.
Contamination of the HEGO sensor can re-
sult from the use of an inappropriate RTV
sealer or silicone spray products. Do not use
silicone sprays or hoses which are assem-
bled using silicone lubricants. Always use
“oxygen sensor safe” RTV sealant for repair
procedures. Silicon contamination will cause
a high but false HEGO signal voltage (rich
exhaust indication). The ECM will then re-
duce the amount of fuel delivery to the
engine, causing a severe driveability prob-
lem. If silicone contamination is suspected,
remove and visually inspect the sensor ele-
ment. If contaminated, the portion of the
sensor exposed to the exhaust stream will
have a white powdery coating. Always be
sure to eliminate the cause of contamination
before replacing the sensor.
When inspecting the Exhaust system check the
following:
Exhaust manifold at the cylinder head for
leaks and that all retaining bolts and shields (if
used) are in place.
Manifold to exhaust pipe fasteners to ensure
they are tight and that there are no exhaust
leaks repair if necessary.
HEGO electrical connector to ensure connec-
tor is seated and locked, check wires to
ensure there is no cracking, splits chafing or
“burn through. Repair if necessary.
Exhaust pipe extension connector for leaks
tighten if necessary.
Visually inspect converter to ensure muffler is
securely mounted and tail pipe is properly
aimed.
Check for any leaks at the inlet and outlet of
the converter.

15
LPG CERTIFIED ENGINE MAINTENANCE REQUIREMENTS
For maintenance or other work that is not performed under warranty, maintenance, replacement, or repair of
the emission control devices and systems may be performed by any engine repair establishment or individual.
Perform the following maintenance on the engine at the hours indicated and at equivalent hour intervals thereafter.
This maintenance schedule represents the manufacturer’s recom-
mended maintenance intervals to maintain proper engine/equipment
function. Federal, State, or Local regulations may require additional or
more frequent inspection or maintenance intervals than those speci-
fied above. Check with the authority having jurisdiction for details.
Interval Hours
Daily 1000 1500 2000 2500 3000 3500 4000 4500 5000
General Maintenance Section
V
isual check for fluid leaks X
Check engine oil level X
Check coolant level X
Change engine oil and filter Every 100 hours or 60 days of operation
Check LPG system for leaks Prior to any service or maintenance activity
Inspect accessory drive belts for cracks, breaks, splits or glazing X X X X X
Inspect electrical system wiring for cuts, abrasions or corrosion X X
Inspect all vacuum lines and fittings for cracks, breaks or hardening X X
Engine Coolant Section
Clean debris from radiator core Every 100 hours or 60 days of operation
Change coolant--GM 6277M specification (Dexcool) 50-50
mixture with distilled water Every 5000 hours or five years
Inspect coolant hoses for cracks, swelling or deterioration X X X X X
Replace coolant hoses and accessory drive bel
t
Every 2,000 hours or two years, whichever occurs first
Engine Ignition System
Inspect Battery case for leaks or damage X X X X X
Inspect battery cables for damage corrosion or contamination X X X X X
Check all electrical connector retainer locks X X X X X
Replace spark plugs X X X
Inspect crank sensor timing wheel for debris or damage Every 100 hours or 60 days of operation
Clean ignition coil X X X X X
Check spark plug wires for cuts abrasions or hardening X
Replace distributor cap and rotor X
Replace spark plug wires X
Fuel System Maintenance
Inspect air cleaner Every 200 hours, or every 100 hours in dusty environment
Replace fuel filters X X X X X
Inspect Shut-off Valve for leaks and closing X X
Leak check fuel lines, regulator, fuel rail and injectors X X
Check air induction and intake manifold for leaks X X
Check manifold for vacuum leaks X X
Drain Regulator oil build up Every 100 hours or 60 days of operation
Engine Exhaust System
Inspect exhaust manifold for leaks X X
Inspect exhaust piping for leaks X X
Check HEGO sensor connectors and wires for burns, cuts or damage X X
Inspect catalyst for mechanical damage X X
Note that propane engines are designed to operate on HD–5 or HD–10 specification LPG fuel. Fuel other than HD–5 or HD–
10 may cause harm to the engine’s emission control system and a warranty claim may be denied on this basis if operators
can readily find the proper fuel*. Use of any other fuel may result in your engine no longer operating in compliance with CARB
or EPA emissions requirements. * Not Applicable in the state of California.

16

17
LPG Fuel System

18
LPG FUEL SYSTEM OPERATION

19
DESCRIPTION AND OPERATION OF THE FUEL
SYSTEMS
LPG FUEL SYSTEM
The primary components of the LPG fuel system
are the fuel storage tank, regulator, throttle control
device, fuel injectors, engine control module (ECM),
catalytic converter and Heated Exhaust Gas Oxy-
gen (HEGO) Sensor.
LPG FUEL TANK
LPG is stored in the fuel tank as a liquid. The ap-
proximate pressure of the fuel in the tank is 16.5
bar (240 psi) when the tank is full at an ambient
temperature of 27° C (81°F). The boiling point,
(temperature at which the liquid fuel becomes va-
por) is approximately -40° C (-40° F). When the
fuel changes from liquid to vapor the fuel expands
and creates pressure inside the tank. When the
tank service valve is opened the pressure inside
the tank forces the liquid fuel out though the pickup
tube located near the bottom of the fuel cylinder.
The service valve mounted in the end of the cylind-
er controls the flow of fuel from the tank. By turning
the handle to its “open” position, fuel flows out of
the tank and into the service line. The service
valve is also equipped with a safety feature called
an excess flow check valve. This feature reduces
the flow from the service valve in the event of a rup-
ture of the fuel line or any downstream fuel
transport components. A safety valve is built into
the tank. Normally set at 25.8 bar (375 psi), it will
release pressure to prevent tank rupture due to
over-pressurization of the cylinder
Typical LPG Cylinder
1. Liquid Outage Fill Check Valve
2. Pressure Relief Valve
3. Liquid Outage valve w/quick disconnect coupl-
ing
4. Filler Valve
5. Fuel Gauge
6. Vapor Withdrawal Tube (when applicable)
7. 80% Limiter Tube
8. Fuel Level Float
9. Liquid Withdrawal Tube
SERVICE LINE
LPG flows from the fuel tank to the Regulator via
the service line connected to the tank utilizing a
quick coupler. The other end of the service line is
connected to a bulkhead connector, allowing for a
safe means of passing through the sheet metal
and into the engine compartment. The service
line is made of high pressure hose with special
material or possibly tubing which is compatible
with the LPG fuel and should always be replaced
with an OEM supplied part.
The bulkhead assembly should never be
removed. Never run a service line through
the sheet metal.
FUEL FILTER
LPG, fuel like all other motor fuels is subject to
contamination from outside sources. Refueling of
the equipment tank and removal of the tank from
the equipment can inadvertently introduce dirt,
rust and other foreign matter into the fuel system.
It is therefore necessary to filter the fuel prior to
entering the fuel system components downstream

20
of the tank. A replaceable, high pressure, inline
fuel filter is built into regulator and another is in
line between the regulator and fuel rail. Mainten-
ance of the filters is critical to proper operation of
the fuel system and should be replaced according
to the maintenance schedule or more frequently
under severe operating conditions.
REGULATOR
The Regulator is a combination vaporizer and pres-
sure regulating device with a built-in LPG shut-off
solenoid valve. The fuel shutoff is a normally
closed valve on the vaporizer, controlled by the
ECM. The valve is opened is opened momentarily
when the ignition is first turned on to allow the sys-
tem to pressurize and when the engine is running.
When open, LPG passes into the regulator and any
liquid LPG is vaporized by heat provided by the en-
gine coolant. The fuel vapor pressure is then
reduced to approximately 88 kPa (12.6 psi) and
delivered to the fuel rail and fuel injectors. The out-
let fuel pressure is referenced to the manifold
pressure for a more stable idle.
Regulator
The regulator and some of components are servi-
ceable.
THROTTLE CONTROL DEVICE—DRIVE BY
WIRE
Speed control is maintained by the amount of pres-
sure applied to the foot pedal located in the engine
compartment, however, in this Drive By Wire
(DBW) application, the foot pedal has an electronic
connection with the throttle and there is no direct
mechanical (cable) connection between the pedal
and the throttle shaft.
The ECM monitors the foot pedal position sensor
when the engine is running. When the operator
depresses or releases the foot pedal, the ECM
sends an electrical signal to the motor on the
electronic throttle to increase or decrease the an-
gle of the throttle blade thereby increasing or
decreasing the volume of air delivered to the en-
gine. Two internal Throttle Position Sensors
(TPSs) provide feedback to the ECM indicating
the position of the throttle shaft and blade. De-
faults programmed into the ECM software ensure
correct speed, load and emission control for all
throttle ranges.
A throttle related failure will cause a “LIMP
HOME” mode of operation, where the engine has
no response to the pedal.
THREE WAY CATALYTIC CONVERTER
The Catalytic Converter is a component of the
emissions system which is designed and cali-
brated to meet the emission standards in effect
for 2011 model year.
The exhaust gases pass through the honeycomb
catalyst which is coated with a mixture of metals
(such as platinum, palladium, and rhodium) to
oxidize and reduce CO, HC and NOx emission
gases.