SERVICE MANUAL
ROBERT BOSCH MODEL MW INJECTION PUMP
Section 11
a portion of the full stroke. Therefore the fuel quantity
delivered per stroke is smaller and the fuel pressure
remains constant. If the return fuel line were blocked at
the fuel check valve assembly or orificed fuel return
hose, the pump pressure would rise to a maximum value
and the supply pump would deliver only the amount of
fuel necessary to maintain the maximum value. This
self-limiting feature protects the injection pump from
excessively high fuel pressures.
Hand Priming Pump Operation
Each injection pump assembly is equipped with a hand
priming pump which is screwed into the supply pump
housing just above the suction valve (Figure 9). With the
aid of the hand priming pump, fuel can be pumped
from the fuel tank through the primary and final fuel
filters into the injection pump. Approximately six
milliliters are delivered per stroke.
To operate the pump, loosen the knurled knob until the
plunger can be pulled upwards. Moving the plunger
upward causes the fuel suction valve to open and fuel to
flow into the suction chamber. When the plunger is
pressed downward, the suction valve closes the
pressure valve opens. Fuel then flows through the
pressure valve and towards the final filter and injection
pump housing. Operate the pump until solid fuel flows
from the final filter bleeder fitting. Always tighten the
knurled knob after operating the pump because engine
operation with the knob loose will damage the hand
priming pump.
Figure 9. - Hand Priming Pump Operation
CGES-185-3
PRINTED IN UNITED STATES OF AMERICA
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