The FCM/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 theMaintenance and Specifcations
section of this supplement.
Fast start glow plug system
The glow plug system consists of:
•eight glow plugs
•the glow plug control module (GPCM)
•engine oil temperature (EOT) sensor
•barometric pressure (BARO) sensor
The glow plug system is
electronically controlled by the
PCM. The GPCM energizes the glow
plugs immediately after the ignition
is placed in the ON position, then determines how long the glow plugs
will be on according to the EOT and BARO sensors. The required time
for the glow plugs to be energized decreases as the engine oil
temperature and barometric pressure increase.
Introduction
4
The complexity of the diesel engine makes it so the owner is discouraged
from attempting to perform maintenance other than the services
described in this supplement.
If you experience difficult starting, rough idling, excessive exhaust
smoke, a decrease in engine performance or excess fuel consumption,
perform the following checks:
•a plugged air inlet system or engine air filter element.
•water in the fuel filter/water separator.
•a clogged fuel filter.
•contaminated fuel.
•air in the fuel system, due to loose connections.
•an open or pinched sensor hose.
•low engine oil level.
•wrong fuel or oil viscosity for climactic conditions.
If these checks do not help you correct the engine performance problem
you are experiencing, consult an authorized dealer.
FUELING
Do not use starting fluid such as ether or gasoline in the diesel
air intake system. Such fluids can cause immediate explosive
damage to the engine and possible personal injury.
If you fuel your vehicle at a truck stop, you may notice that the fuel
nozzle may shut off every 5–10 seconds. This is due to the flow rates
being designed for larger heavy duty trucks. You may have to fuel at a
slower rate (don’t depress the nozzle trigger fully).
Do not run your diesel vehicle out of fuel as this will allow air to enter
the fuel system which will make restarting difficult. Longer engine
cranking time may be required once air is in the fuel system. If air enters
the fuel system (either through running the fuel tank(s) empty or during
a fuel filter change), the engine will self-purge the trapped air once it
starts running. The engine may run roughly and produce white smoke
while air is in the fuel system; this is normal and should stop after a
short time.
MINOR TROUBLESHOOTING GUIDE
If the engine won’t crank
Turn on the headlights. If the lights are dim, do not go on at all or if
when the ignition is turned to 5 (START) the lights become dim or go
Maintenance and Specifications
45
