TM-9-2320-272-24-3
TRUCK, 5-TON, 6X6, M939, M939A1, AND M939A2 SERIES TRUCKS (DIESEL)
TECHNICAL MANUAL; UNIT, DIRECT SUPPORT, AND GENERAL SUPPORT MAINTENANCE MANUAL; VOLUME 3 OF 4
JUNE 1998
TM-9-2320-272-24-3 - Page 72 of 799
TM 9-2320-272-24-3
4-56. FUEL INJECTOR CALIBRATION
THIS TASK COVERS:
a. Opening Pressure Test
b. Leakage Test
c. Spray Pattern Test
INITIAL SETUP:
APPLICABLE MODELS
M939A2
SPECIAL TOOLS
Tube reducer (Appendix E, Item 151)
Injector nozzle tester (Appendix E, Item 71)
TOOLS
General mechanic’s tool kit (Appendix E, Item 1)
Diesel fuel (Appendix C, Item 42)
REFERENCES (TM)
TM 9-2320-272-24P
EQUIPMENT CONDITION
Fuel injector removed (para. 4-55).
GENERAL SAFETY INSTRUCTIONS
l
All personnel must keep hands clear of test spray.
l
Diesel fuel is flammable. Do not perform this task
near open flame.
WARNING
Keep hands and body clear of test spray. Pressure of diesel fuel is
sufficient enough to penetrate skin, causing injury to personnel.
Diesel fuel is flammable. Do not perform fuel system procedures
near open flame. Injury to personnel or damage to equipment
may result.
Use clean diesel fuel when calibrating injector.
Fuel injectors are calibrated the same. This procedure covers
calibration of one injector.
1.
Install tube reducer (3) on injector (2).
2.
Install test line (11) to adapter (3).
3.
Open valve on injector nozzle tester.
Operate lever on injector nozzle tester one stroke per second.
4.
Operate lever on injector nozzle tester until injector (2) ejects test spray.
5.
Observe pressure indicator on pressure gauge when spray begins.
6.
Correct pressure reading should be 2,973 psi (20,499 kpa).
Shim is located below pressure spring.
Increasing shim thickness will increase opening pressure.
Decreasing shim thickness will decrease opening pressure.
7.
If opening pressure deviates from limits, change shim inside of injector (2), as required (para. 4-55).
b. Leakage Test
1.
Open valve on injector nozzle tester.
4-336
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