TM-9-2320-272-24-4

TRUCK, 5-TON, 6X6, M939, M939A1, AND M939A2 SERIES TRUCKS (DIESEL)

TECHNICAL MANUAL; UNIT, DIRECT SUPPORT, AND GENERAL SUPPORT MAINTENANCE MANUAL; VOLUME 4 OF 4

JUNE 1998

  TM-9-2320-272-24-4 - Page 280 of 836

TM 9-2320-272-24-4
5-37. FUEL INJECTION PUMP CALIBRATION (Contd)
g. Full Load Delivery
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.
Apply 13.05 psi (90 kPa) of air to manifold pressure compensator (6).
Adjust fuel pump (7) to 1,050 rpm.
Set fuel test stand to measure fuel delivery at 1,000 strokes.
Reduce fuel pump (7) to 700 rpm.
Position control lever (8) to full load position.
Take fuel draw and observe delivery quantity. Correct delivery quantity should be 9.1-9.2 in.
3
(149.1-150.8 cm
3
).
Check spread reading. Correct spread reading is 0.366 in.
3
(6.00 cm
3
).
Close air supply source to manifold pressure compensator (6).
Reduce fuel pump (7) to 500 rpm.
Position control lever (8) to full load position.
Take fuel draw and observe delivery quantity. Correct delivery quantity is 4.8-4.9 in.
3
(78.7-80.3 cm
3
).
NOTE
Perform steps 12 through 14 if fuel delivery quantity deviates
from specifications.
Remove breakoff screw (10), screw (1), two lockwashers (3), protective cap (4), and stop (5) from
manifold pressure compensator (6). Discard two lockwashers (3) and breakoff screw (10).
Turn nut (9) clockwise to increase fuel delivery; counterclockwise to decrease fuel delivery.
Install stop (5) and protective cap (4) on manifold pressure compensator (6) with two new lock-
washers (3), new breakoff screw (11), and screw (1).
Install new safety wire (2) on screw (1) and protective cap (4).
5-274


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