3-93. ON-ENGINE FUEL PUMP ADJUSTMENT (Contd)
18. Threaded stud (24)
To adjust fuel rail pressure:
Do not turn threaded stud out beyond maximum throttle travel. The fuel hole in the throttle
shaft will begin to close. Never adjust fuel rail pressure above maximum specifications.
This will void engine warranty and violate EPA requirements.
a. Turn out to get maximum
This will reduce throttle
throttle travel. Secure with
b. Remove throttle shaft ball (20).
Refer to para. 3-62.
c. Turn fuel adjusting screw (22)
in throttle shaft (21) in to increase
or out to decrease pressure while
watching fuel rail pressure
d. It should not be necessary to
adjust fuel manifold pressure on
a newly calibrated pump more
than ± 2 psi (± .14 kPa). If
adjustments greater than these
are required, fuel pump test,
injector test stand, or engine
problems may exist.
e. Install throttle shaft ball (20)
into end of throttle shaft (21) with
throttle shaft ball installing tool
(3375204) (25) after adjustment.
f. Checking and Adjusting Engine Fuel
19. Fuel pump assembly (3)
Connect suitable fuel rate meter
The fuel rate specified on fuel pump calibration specifications is at full throttle and rated
speed. An engine or chassis dynamometer must be used. Accurate fuel rail pressure and
speed readings must also be taken.
20. Engine (1)
a. Bring engine (1) to full throttle and
increase dynamometer load until
engine rpm falls to rated speed.
b. Check governor speed cut-off
while a load is on engine (1).
c. Check fuel rail pressure
gauge (19) at maximum speed.
d. Hold engine speed and load at
maximum speed long enough for
fuel rate meter (26) to stabilize.
e. Verify correct fuel rate measure-
ment with fuel rate meter (26).