Engine System, Gasoline/LPG
97
Service Manual – Advance 7765 / Nilfisk CR1500
Circuit Description
• For the engine to start:
– The
Ignition Switch
must provide positive voltage to the
Ignition
terminal
A
on the
14-pin Engine Harness
Connector
.
– The
St.
(start) terminal on the
Ignition Switch
must provide positive voltage to the
Start/Crank Power
terminal
K
on the
14-pin Engine Harness Connector
.
• For the engine to run, the coolant temperature and oil pressure must be within acceptable parameters.
GM 3.0L Gasoline Fuel System Description
This engine is equipped with a fuel injector rail that does not have a pressure regulator or a return circuit to
the fuel tank. Fuel pressure for this engine is regulated by the engine’s Engine Control Module (ECM). The
ECM receives fuel pressure and temperature feedback from the gasoline fuel sensor manifold and uses this
information to control the ground side of the fuel pump.
Fuel pressure is regulated by the ECM pulse width modulating (PWM) the fuel pump. The fuel pressure and
temperature sensor manifold has a return or “bleed” circuit that connects back to the equipment fuel tank.
This circuit is used to bleed off any vapor that develops in the line and returns a small amount of fuel to the
tank.
The fuel comes from the fuel tank and passes through the fuel pump. Fuel exits the fuel pump, passes
through the filter and then enters the fuel pressure and temperature manifold assembly. Fuel flows through
the feed circuit and is delivered to the fuel injector rail. Fuel that enters the bleed circuits through the
bypass valve in the manifold is returned to the fuel tank.
GM 3.0L LPG Fuel System Description
The fuel system on LPG engines includes a Direct Electronic Pressure Regulator (DEPR), air/fuel mixer,
Electronic Throttle Control (ETC) device and an Engine Control Module (ECM).
An Electric Fuel lock-off valve, consisting of a 12 volt solenoid and a normally-closed valve, opens during
cranking and engine run cycles. The ECM controls the voltage to the Electric Fuel lock-off valve.
The DEPR is an electromechanical fuel pressure regulator that communicates with the ECM to regulate
the fuel pressure. The air/fuel mixer is a self-contained air-fuel metering device that is mounted in the air
stream ahead of the throttle control device. The ECM and the ETC control the engine speed.
Note:
For a more detailed and thorough description of the LPG fuel system, refer to the
PSI Tier 3
Certified Mobile Diagnostic and Troubleshooting Manual
, publication number
PSITIER3 - G
.
Summary of Contents for 56514925
Page 28: ...General Information 28 Service Manual Advance 7765 Nilfisk CR1500 Maintenance Item Locations ...
Page 74: ...Engine System common Electrical System 74 Service Manual Advance 7765 Nilfisk CR1500 ...
Page 89: ...Engine System Diesel 89 Service Manual Advance 7765 Nilfisk CR1500 Starter Relay ...
Page 113: ...Engine System Gasoline LPG 113 Service Manual Advance 7765 Nilfisk CR1500 ...
Page 114: ...Engine System Gasoline LPG 114 Service Manual Advance 7765 Nilfisk CR1500 ...
Page 115: ...Engine System Gasoline LPG 115 Service Manual Advance 7765 Nilfisk CR1500 ...