TM-9-2320-272-24-2
TRUCK, 5-TON, 6X6, M939, M939A1, AND M939A2 SERIES TRUCKS (DIESEL)
TECHNICAL MANUAL; UNIT, DIRECT SUPPORT, AND GENERAL SUPPORT MAINTENANCE MANUAL; VOLUME 2 OF 4
JUNE 1998
TM-9-2320-272-24-2 - Page 690 of 991
TM 9-2320-272-24-2
Table 4-1. Mechanical Troubleshooting (Contd).
MALFUNCTION
TEST OR INSPECTION
CORRECTIVE ACTION
15. EXCESSIVE FUEL CONSUMPTION
Check fuel injectors for proper operation and adjustment (para. 4-33, 4-34, or 4-56).
END OF TESTING!
16. ENGINE SURGES AT IDLE SPEED
Perform malfunction 2.
END OF TESTING!
17. ENGINE SURGES AT ALL SPEEDS
Replace or repair fuel pump (para. 4-35 or 4-57).
END OF TESTING!
18. EXCESSIVE EXHAUST SMOKE AT IDLE, AND UNDER LOAD
Step 1. Perform malfunction 2.
Step 2. Check cylinder head for damaged and burned valves.
Replace or repair cylinder head (para. 4-12 or 4-41).
Step 3. Check cylinder liners for scoring and wear.
If scored or worn, replace cylinder liners (para. 5-7 or 5-28).
Step 4. Check pistons and piston rings for wear and damage.
If worn or damaged, replace as necessary (para. 5-10 or 5-26).
END OF TESTING!
19. ENGINE FAILS TO STOP
NOTE
This malfunction pertains to M939 and M939A1 series vehicles.
Check fuel shutoff solenoid for proper operation.
If defective, replace fuel shutoff valve (para. 4-36 or 4-37).
END OF TESTING!
20. ENGINE MISSES
Step 1. Perform malfunction 2.
Step 2. Check cylinder head for damaged and burned valves.
Replace or repair cylinder head (para. 4-12 or 4-41).
END OF TESTING!
21. LOW POWER OR LOSS OF POWER
Step 1. Perform malfunction 2.
Step 2. Check cylinder head for damaged and burned valves.
Replace or repair cylinder head (para. 4-12 or 4-41).
END OF TESTING!
4-8
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