Operation and maintenance manual

Section 200-0040
Fuel System - Fuel System
SM 1398 Rev 1 2-00
2
When installing fuel lines, it is recommended that
connections be tightened only sufficiently to prevent
leakage of fuel; thus flared ends of the fuel lines will
not become twisted or fractured because of excessive
tightening.
A fuel tank breather/filter assembly is incorporated into
the fuel filler cap (24), allowing fuel tank (1) to vent to
atmosphere, preventing pressure from building up
within fuel tank (1) assembly.
OPERATION
Numbers in parentheses refer to Fig. 1.
Fuel is drawn from fuel tank (1) through primary fuel
filter (3) and enters fuel pump (5). Leaving fuel pump
(5) under pressure, the fuel flows through ECM cooling
plate (7), through secondary fuel filter (9) to the engine
cylinder head. The fuel flows to electronic unit injectors
(15) in the cylinder head through passages integral with
the cylinder head. Surplus fuel exits at the rear of the
cylinder head just above the inlet, flows through fuel
cooler (16) and back to fuel tank (1). Restricted fitting
(23) at rear of engine maintains fuel pressure in the
system.
REMOVAL
Numbers in parentheses refer to Fig. 1.
WARNING
To prevent personal injury and property
damage, be sure wheel blocks, blocking
materials and lifting equipment are properly
secured and of adequate capacity to do the job
safely.
1. Position the vehicle in a level work area, apply the
parking brake and switch off the engine. Operate
steering right and left several times to relieve pressure
in the steering system.
2. Block all road wheels and place the battery master
switch in the 'Off' position.
3. If required, remove mounting hardware securing the
front grille on the hood assembly and remove grille for
access to the fuel cooler (16).
4. Pull on handle to release hood catch mechanism
and raise hood.
5. Remove padlock (20) and remove filler cap (24) from
fuel tank (1).
Fuel pump (5) is attached to a drive assembly mounted
on the rear side of the gear case at the front LH side of
the engine and transfers fuel from fuel
tank (1) to the electronic unit injectors (15).
The electronic unit injector (15) is a lightweight,
compact unit that injects diesel fuel directly into the
combustion chamber. The amount of fuel injected and
the beginning of injection timing is determined by the
ECM. The ECM sends a command pulse which
activates the injector solenoid.
The EUI performs four functions:
a - Creates the high fuel pressure required for efficient
injection.
b - Meters and injects the exact amount of fuel required
to handle the load.
c - Atomizes the fuel for mixing with the air in the
combustion chamber.
d - Permits continuous fuel flow for component cooling.
Electronic unit injectors are self compensating and
virtually eliminate engine tune-ups.
Note: Never apply 12 V directly to terminals on the
injector as it will burn out. Before removing injectors,
the fuel passages must be blown out to prevent fuel
flow from entering the cylinder head.
ECM cooling plate (7) is mounted in front of the ECM
on the LH side of the engine and absorbs heat
generated by the ECM. Fuel from fuel pump (5) outlet
line (6) flows through ECM cooling plate (7) to absorb
this heat.
Fuel cooler (16) is mounted on the front of the radiator
and cools fuel returning to fuel tank (1).
Flexible fuel lines (2, 4, 6, 8, 13, 14 & 22) are used to
facilitate connection of lines leading to and from fuel
tank (1), and to minimize the effects of any vibration in
the installation. A 2.03 mm (0.08 in) restricted orifice is
incorporated in the fuel return fitting (23) at rear of
engine to maintain fuel pressure in the system. The
restricted orifice is designed to provide the proper fuel
system pressure under all conditions.
Note: Do not alter or substitute another size of orifice
since this may alter engine performance and
emissions.
Note: Do not use restricted fittings anywhere else in
the fuel system and do not substitute a standard fitting
for the restricted fitting.