DIESEL ENGINE INFORMATION
The Diesel engine fuel system consists of:
•an engine-mounted secondary fuel filter
•frame-mounted Horizontal Fuel Conditioner Module (HFCM)
•a unit injector for each cylinder
The HFCM acts as a primary fuel filter/water separator which removes
both water and impurities from the fuel. The engine-mounted fuel filter
and the HFCM filter should be changed at the recommended service
interval. Refer to theScheduled maintenance guidesection of this
manual for more information.
The HFCM should be drained at
regular intervals or when the
WATER IN FUEL light illuminates in
the instrument cluster.
The fuel injectors are located in the center of the combustion chambers
in the cylinder head between the rocker arm assemblies. The glow plug
system and fuel injection system are controlled through the Powertrain
Control Module (PCM) and Fuel Injection Control Module (FICM).
Fuel is drawn from the fuel tank by a frame-mounted electric fuel pump.
The fuel pump provides pressurized fuel to the engine and is
electronically controlled by the fuel pump PCM relay. The fuel pump
contains a pressure relief valve for overpressure protection in the event
of restricted flow.
Lubrication system
It is important to change the engine oil at the recommended service
intervals, because oil viscosity is important in maintaining the oil
pressure required to actuate the fuel injectors. Extended oil change
intervals can negatively affect engine performance, fuel economy and
engine life. Refer to the engine oil specification chart located under
Engine oil specificationsin theGeneral maintenance information
chapter.
Diesel information
4
