HIGH PRESSURE SIDE
A. Filling the piston: The piston is moved down
as a result of the piston spring. The fuel supplied by
the fuel delivery pump flows along the ring passage,
the valve disk and the valve spring into the cylinder.
The ball valve prevents the fuel from being able to
flow back from the high pressure passage.
B. Producting high pressure:The piston is
moved up by the rising eccentric shaft and the fuel is
thus compressed. The valve disk shuts off the deliv-
ery volume to the fuel feed. Once the fuel pressure in
the cylinder rises beyond the pressure which exists
in the high pressure circuit, the ball valve opens and
the fuel is pumped into the high pressure circuit.
OPERATION - LOW PRESSURE PUMP
The low pressure pump draws fuel from tank
through fuel filter and supplies the high pressure
pump. Fuel pressure at starter speed is 0.4 to 1.5 bar
(6 to 22 psi.). A fuel pressure of 2.0 to 2.5 bar (29 to
36 psi.) is reached at idle speed. Fuel pressure is lim-
ited to 3.5 bar ± .5 bar (51 psi. ± 7 psi) by the valve
in the fuel delivery pump. This valve opens by over
coming a spring force and allows excessive fuel to
flow to the intake side of the low pressure pump.
This diverted fuel flows into the return flow pipe
through the fuel cooler back to the tank. As a result
of this circulation, the fuel always remains relatively
cool.
REMOVAL
REMOVAL - HIGH PRESSURE PUMP
WARNING: NO SPARKS, OPEN FLAMES OR SMOK-
ING. RISK OF POISONING FROM INHALING AND
SWALLOWING FUEL. RISK OF INJURY TO EYES
AND SKIN FROM CONTACT WITH FUEL. POUR
FUELS ONLY INTO SUITABLE AND APPROPRI-
ATELY MARKED CONTAINERS. WEAR PROTECTIVE
CLOTHING.
(1) Disconnect negative battery cable.
(2) Remove engine cover (Refer to 9 - ENGINE -
REMOVAL).
(3) Remove accessory drive belt (Refer to 7 -
COOLING/ACCESSORY DRIVE/DRIVE BELTS -
REMOVAL).
(4) Partially drain coolant system (Refer to 7 -
COOLING/ENGINE/COOLANT - STANDARD PRO-
CEDURE).
(5) Disconnect viscous heater hose at heater and
bracket above idler pulley and set aside.
(6) Disconnect hydraulic fan power steering hose
at steering pump and set aside.
(7) Remove bolt for fuel line retainer at lifting eye.
CAUTION: DO NOT slacken the threaded connec-
tion. Use a wrench to counterhold at the threaded
connection when loosening and tightening the
union nut. DO NOT EXCEED tightening torque.
CAUTION: DO NOT crimp or bend fuel line. Capture
all fluids that flow out of connections.
(8) Unbolt pressure line at pressure pump.
(9) Detach fuel return flow line at high pressure
pump.
NOTE: Detach high pressure pump driver and inter-
mediate piece if pump is being replaced.
(10) Remove bolts attaching high pressure pump
and remove pump (Fig. 3).
Fig. 2 VACUUM PUMP AND LOW PRESSURE FUEL
PUMP ASSEMBLIES
1 - VACUUM LINE
2 - FUEL OUTLET LINE
3 - FUEL FEED LINE
4 - LOW PRESSURE FUEL PUMP
5 - VACUUM PUMP
14a - 14 FUEL DELIVERY WG
FUEL PUMP (Continued)
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