TM-9-2320-260-34-1
TRUCK, 5-TON, 6X6, M809 SERIES (DIESEL)
TECHNICAL MANUAL; DIRECT SUPPORT AND GENERAL SUPPORT MAINTENANCE; VOLUME 1 OF 2
JULY 1994
TM-9-2320-260-34-1 - Page 16 of 657
TM 9-2320-260-34-1
2-6. GENERAL TROUBLESHOOTING INSTRUCTIONS (Contd)
b.
Perform the easiest and most obvious troubleshooting tasks and corrections first. Most malfunctions
are easily corrected. For example:
(1)
Low power problems are generally caused by loose throttle linkage or dirty fuel or air filters.
(2)
Excessive oil consumption is generally caused by leaky gaskets or loose line connections.
c.
Double check before disassembly. The source of most engine problems can be traced to more than one
part in a system. For example:
(1)
Excessive fuel consumption may not be caused by the fuel pump alone. Instead, the trouble could
be a clogged air cleaner reducing air inflow or a restricted passage causing abnormally high back pressure.
(2)
Engines very often are disassembled in search of a complaint and the real evidence of the problem
is destroyed. Check again to be sure an easier solution to the problem has not been overlooked.
(3)
Check all tags, service request forms, and vehicle logbook for repair history. This may help lead to
the source of problems.
d.
Before attempting to correct a problem, diagnose the cause of the problem. Do not allow the same
malfunction to reoccur.
MECHANICAL SYSTEMS TROUBLESHOOTING
SYMPTOM INDEX
MALFUNCTION
TROUBLESHOOTING
NO.
MALFUNCTION
PROCEDURE
PAGE
1.
2.
3.
4.
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.
16.
17.
18.
19.
20.
21.
22.
23.
24.
25.
26.
5.
ENGINE
Engine will not crank . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2-5
Engine cranks slowly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2-6
Engine cranks but will not start . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2-6
Engine starts, won’t run . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2-6
Engine stops when throttle is returned to idle position . . . . . . . . . . . . . .
2-6
Engine has poor acceleration and/or lack of power . . . . . . . . . . . . . . . . .
2-6
Black exhaust smoke at idle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2-7
Engine surges . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2-7
Engine misfires during normal operation . . . . . . . . . . . . . . . . . . . . . . .
2-7
Engine stops during normal operation (engine restarts) . . . . . . . . . . . . .
2-7
Engine stops during normal operation (engine does not restart). . . . . . . .
2-7
Exhaust color blue during normal operation . . . . . . . . . . . . . . . . . . . . .
2-8
Exhaust color white during normal operation and idle . . . . . . . . . . . . . .
2-9
Engine oil pressure low at normal engine operating temperature. . . . . . .
2-9
Engine oil pressure extremely high at normal operating temperature . . .
2-9
Engine oil pressure zero . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2-10
Engine oil loss during normal operation . . . . . . . . . . . . . . . . . . . . . . . .
2-10
Engine noise abnormal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2-10
Engine vibration abnormal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2-11
FUEL SYSTEM
No fuel at fuel injectors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2-12
Lean fuel flow at injectors – low power – loss of power . . . . . . . . . . . . . .
2-12
Excessive exhaust smoke at idle and under load - excessive fuel
consumption . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2-12
Engine idle rough, erratic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2-13
Engine overspeeds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2-13
Engine lubricating oil diluted by fuel . . . . . . . . . . . . . . . . . . . . . . . . . .
2-13
Engine knocks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2-13
2-2
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