3-93. ON-ENGINE FUEL PUMP ADJUSTMENT (Contd)
g. Checking and Adjusting Throttle
If throttle leakage is adjusted correctly on fuel pump test stand, fuel pump will not need to
be adjusted on engine. Vehicle throttle linkage must be adjusted so that threaded stud of
throttle leakage adjusting screw (rear screw) just contacts stop on pump throttle.
21. Engine (1)
a. Bring engine to full throttle and
The purpose of the throttle
allow engine to run at maximum
leakage is to keep the fuel lines
and injector drilling full of fuel
during closed throttle operation.
The correct throttle leakage will
help acceleration when the throt-
tle is opened after going down a
grade. Throttle leakage will also
prevent stalling when it slows
down to the idle speed. (Too much
leakage will cause slow decelera-
b. Release or move throttle
quickly and start a suitable timer
or stopwatch at the same time.
c. Stop timer when 1000 rpm
is reached and check decelera-
tion time. Repeat this check
d. Increase leakage if engine (1)
begins to stall (idle governor does
catch engine after deceleration
from high idle).
22. Threaded stud (27)
a. Increase leakage by
b. Recheck engine (1) deceleration
until time is increased 1-2 seconds.
c. Lock threaded stud (27) with
d. Recheck idle speed and
readjust as necessary.
e. Set engine to high idle.
f. Check deceleration time when
If deceleration time is not faster
shutoff valve is closed (engine (1)
by this method, throttle leakage
is shut down).
is not the problem. If the
deceleration time is faster by this
method, throttle leakage must be