indicates that a leak is present. The pressure must remain
7-86. Fuel Injection
above 250 psi for at least 30 seconds.
Test, After Rebuilding.
(1) Turn pump upside down and depress tappet
with thumb. Tappet should recede 1/16-inch into face gear
If tappet cannot
be depressed 1/16-inch into face
gear, plunger sleeve pin (5, fig. 7-46) is improperly alined.
(2) Remove the overflow valve assembly from
the fuel outlet hole in the pump housing. Install a 1/4-inch
(3) Secure the pump close to a nozzle test stand.
(9) Visual inspection should be as follows:
(5) Install C-clamp on injection pumps to retain
(a) Check for leakage by the head locating
screw (13, 7-46).
(6) Aline holes in face gear and housing
(b) Fuel leakage at the control unit (4)
indicates that either the O-ring (33) is damaged or the
control unit is defective. Replace entire injection pump.
(c) Check for leakage of fuel around the
A fuel inlet stud can be fabricated with a 1/4-18
face gear (28). If leakage is evident, disassemble pump and
NPT pipe die. High pressure tubing must be
inspect O-ring (19). If O-ring is damaged, replace injection
used between test stand and the pump
assembly. Always ensure that all external
connections are tight and that the nozzle test
(d) Check for fuel leakage between top of
stand is in good order.
housing and head flange. Disassemble and check O-ring.
If O-ring is damaged, replace injection pump.
(7) Connect the nozzle test stand to the fuel inlet
b. On Equipment Adjustment and Timing.
hole in the pump housing.
(1) Timing. Time the injection pump to the
engine by using the proper thickness timing button
method 1 when replacing an old pump if the port closing
Do not exceed a pressure of 400 psi.
dimensions and button number of the old pump were
recorded. Use method 2 if the dimensions are-lost; an old
pump is being timed, or when replacing either camshaft or
(8) Slowly operate the nozzle test stand until a
pressure of 400 psi is achieved. A rapid drop in pressure