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 268 of 836
TM 9-2320-272-24-4
5-37. FUEL INJECTION PUMP CALIBRATION
THIS TASK COVERS:
a.
Prestroke and Back Travel
b.
Cylinder Phasing (Timing)
c.
Lock Timing
d.
High-speed Fuel Delivery Test
e.
Low-speed Fuel Delivery Test
f.
Bated Speed Test
g.
Full Load Delivery
h.
Manifold Pressure Compensator Test
i.
Fuel Delivery Test
j.
Fuel Breakaway Test
k.
Starting Fuel Delivery Test
l.
Low Idle Fuel Delivery Test
m. External Stop Setting
INITIAL SETUP:
APPLICABLE MODELS
M939A2
SPECIAL TOOLS
Plunger lift device (Appendix E, Item 98)
Rack extension (Appendix E, Item 112)
TOOLS
General mechanic’s tool kit (Appendix E, Item 1)
Dial indicator (Appendix E, Item 36)
MATERIALS/PARTS
Two copper washers (Appendix D, Item 44)
Two break off screws (Appendix D, Item 19)
Two lockwashers (Appendix D, Item 397)
Copper washer (Appendix D, Item 42)
Two breakoff screws (Appendix D, Item 20)
Four lockwashers (Appendix D, Item 398)
Lubricating oil (Appendix C, Item 50)
Safety wire (Appendix C, Item 79)
REFERENCES (TM)
TM 9-2320-272-24P
TM 9-4910-778-14&P
EQUIPMENT CONDITION
l
Fuel injection pump repaired (para. 5-36).
l
Fuel injection pump mounted to test stand
(para. 5-31).
NOTE
Refer to TM 9-4910-778-14&P for operation of fuel injection pump
test stand, DFP 156.
1.
2.
3.
4.
5.
6.
7.
8.
9.
Mount dial indicator (2) and rack travel indicator holder (1) on drive end of fuel pump (5).
NOTE
Cylinder number one is located at drive end of fuel injection pump.
Install plunger lift device (8) on fuel pump (5) with finger of lifting device (8) resting on top of
tappet located in cylinder number one.
Mount dial indicator (7) on lifting device (8) and zero dial indicator (7).
Pull control lever (6) to full load position and using dial indicator shaft (3), push control rack (4) all
the way back.
Preload dial indicator (2) giving control rack (4) 0.004 in. (0.1 mm) of preload travel.
Manually rotate test stand driveshaft (9) until a reading is observed on dial indicator (7).
Manually reverse rotation test stand driveshaft (9) until dial indicator (7) reads zero.
Manually rotate test stand driveshaft (9) clockwise and take prestroke measurement from dial
indicator (7). Correct prestroke measurement should be 0.120-0.128 in. (3.05-3.25 mm).
If correct prestroke measurement is not obtained, perform steps 10 through 13.
5-262
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