5.36
Section 5
EFI Fuel System
EFI Diagnostic Flow Diagram
Figure 5-30. Troubleshooting Flow Chart.
START OF TEST
KEY ON
MALFUNCTION
INDICATOR LIGHT
ON
ARE FAULT CODES
PRESENT?
NO
DOES ENGINE START?
NO
CRANK ENGINE.
DOES MIL GO OFF?
YES
KEY OFF AND KEY ON
1
.
LISTEN FOR FUEL PUMP.
DOES FUEL PUMP CYCLE
ON THEN OFF AFTER 1–2
SECONDS
2
?
YES
WHILE CRANKING, CHECK
IGNITION SYSTEM
SPARK?
YES
WHILE CRANKING, CHECK
INJECTOR FUEL DELIVERY.
WET SPARK PLUG?
YES
INSTALL IN-LINE PRESSURE
GAUGE AND KEY ON.
FUEL PRESSURE
IN SPECIFICATION?
NO
YES
YES MIL GOES OFF?
YES
NO
NO
NO
NO
NO
YES
REFER TO DIAGNOSTIC AID #1
SYSTEM POWER
REFER TO DIAGNOSTIC AID #2
FAULT CODES
CLEAR CODES
NO
REFER TO DIAGNOSTIC AID #3
RUN/ON
OPERATE AT VARIOUS SPEED/
LOAD CONDITIONS
ARE FAULT CODES
PRESENT?
NO
END OF TEST
REFER TO DIAGNOSTIC AID #4
CRANKSHAFT POSITION SENSOR
REFER TO DIAGNOSTIC AID #5
FUEL PUMP
REFER TO DIAGNOSTIC AID #6
IGNITION SYSTEM
REFER TO DIAGNOSTIC AID #7
FUEL SYSTEM ELECTRICAL
REFER TO DIAGNOSTIC AID #8
FUEL SYSTEM
REFER TO DIAGNOSTIC AID #9
BASIC ENGINE
YES
REFER TO DIAGNOSTIC
AID #2 FAULT CODES
CLEAR CODES
PROCEED TO START OF TEST FOR RETEST
PROCEED TO START OF TEST FOR RETEST
1. After turning key to OFF, wait 10 seconds before turning to ON to allow the ECU to go to sleep.
2. The fuel pump module can be heard or a vibration can be felt to establish pump cycle. Fuel pump module
will run for one 4-6 second cycle when ECU wakes up after being asleep.
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