TM-9-2320-280-20-1
TRUCK, UTILITY: M998 SERIES
TECHNICAL MANUAL; UNIT MAINTENANCE; VOLUME 1 OF 3
JANUARY 1996
TM-9-2320-280-20-1 - Page 195 of 888
2-108
Change 2
B4
KNOWN INFO
FUEL SOLENOID AND
WIRING OK
FUEL RETURN LINES
INJECTION PUMP
INJECTORS
RETURN CHECK
VALVE
POSSIBLE PROBLEMS
TM 9-2320-280-20-1
FUEL SYSTEM
DIAGNOSTIC FLOWCHART
TEST OPTIONS
Visual Inspection
REASON FOR QUESTION
Plugged fuel return lines
cause back pressure which
prevents injection pump from
working properly.
KNOWN INFO
RETURN LINES OK
INJECTION PUMP
INJECTORS
POSSIBLE PROBLEMS
TEST OPTIONS
Run Intake/Exhaust Tests
Page 2-137.
REASON FOR TESTS
There is still a possible
Intake/Exhaust fault. If you
came here from Startability
then this wasn’t tested.
B5
NO
YES
Repair/Replace
Fuel Injector
Return Lines
From B3
Page 2-106
DOES THE ENGINE RUN
POORLY WITH THE RETURN
LINE DISCONNECTED?
RUN THE INTAKE/EXHAUST
TESTS.
RETURN HERE IF NO FAULTS
FOUND.
KNOWN INFO
RETURN LINES OK
INJECTION PUMP
INJECTORS
POSSIBLE PROBLEMS
TEST OPTIONS
Run Startability Test
Page 2-41.
Run Fuel System Test
Page 2-95.
REASON FOR TEST
If all efforts have been
exhausted, still experience
no hot start problem, identify
the fuel injection pump model
and serial number.
B6
RUN THE STARTABILITY TEST
RUN THE FUEL SYSTEM TEST
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