TM 9-2320-272-24-4
5-18. FUEL PUMP SETUP AND CALIBRATION (Contd)
d. Testing Pump Seals for Leaks
CAUTION
Check tachometer drive for clockwise rotation. If rotation is not
l
clockwise, reverse rotation of drive coupling.
l Do not leave fuel pressure valve closed more than five minutes
because pump could overheat and be damaged.
NOTE
All steps must be completed before pump is considered calibrated.
1.
With test stand (2) operating at 500 rpm, close fuel pressure valve (7).
2.
Place test stand fuel flow control valve (1) to OPEN position. If 25 in. vacuum is not obtained, check
all hose connections.
3.
Place bypass valve (8) in closed position.
4.
Apply a small amount of GM grease over vent of weep hole (12). If grease is pulled into weep
hole (12) at 25 in. vacuum, fuel pump (10) oil seal is defective and fuel pump (10) must be replaced
(para. 4-35).
5.
Open fuel pressure valve (7).
e . Testing Governor Cutoff RPM
Open test stand fuel flow control valve (1) completely.
1.
2.
Increase fuel pump (10) speed to 2,100 rpm by depressing and releasing FAST (5) or SLOW (6)
button.
3.
Adjust test stand fuel flow control valve (1) to obtain 8 in. Mercury (HG) on vacuum gauge (4).
NOTE
Once 8 in. HG vacuum setting is obtained, do not change setting.
Readings will fluctuate during other tests. Just note the increases
or decreases as they occur.
4.
Open the fuel flow control valve (1) and place the selector valve (9) in ROTAMETER position.
5.
Increase pump (10) speed until the fuel pressure drops. Stand tachometer (3) reading should be
2,130-2,150 rpm. Depress and release FAST (5) or SLOW (6) button to increase or decrease rpm.
The VALVES governor automotive governor portion is set 100 rpm higher.
CAUTION
Test stand must be shut off to change shims in spring pack.
NOTE
l Perform steps 6 and 7 only if spring pack shims are changed.
l Each .001 in. (0.25 mm) shim thickness will change speed
approximately two rpm.
l Shims are available in 0.005, 0.010, and 0.020 in. (0.13, 0.25,
and 0.51 mm) thicknesses.
6.
If cutoff is too low, remove spring pack (11) and add shims. If cutoff is too high, remove shims
7.
With fuel pump (10) at 500 rpm, move throttle lever (13) back and forth until ROTAMETER shows
no air and recheck governor cutoff rpm, steps 1 through 6.
5-110
