Mercury MerCruiser MCM 454 Mag MPI Service Manual page 588

SERVICE MANUAL NUMBER 23
Dieseling, Run-On Symptom
Step
Definition: Engine continues to run after key is turned "OFF," but runs very rough. If
engine runs smooth, check ignition switch and adjustment.
Index
90-861326--1 MARCH 1999
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Action
Was the "On-Board Diagnostic" (OBD)
1
System Check performed?
Was visual/physical check performed?
2
1. Check for leaking fuel injectors.
Refer to Table A-4 in "General Sys-
tem Diagnostics" section.
3
2. If a problem is found, repair as nec-
essary.
Was a problem found?
1. Check for proper operation of Igni-
tion Control (IC) circuit and the
Knock Sensor (KS) circuit.
4
2. If a problem is found, repair as nec-
essary.
Was a problem found?
1. Check for obvious overheating
problems:
Loose water pump belt.
Faulty or incorrect water pump.
5 Restriction in cooling system.
Faulty or incorrect thermostat.
2. If a problem is found, repair as nec-
essary.
Was a problem found?
1. Check for proper operation of the
EFI system relay.
Refer to Table A-6 in "General Sys-
6
tem Diagnostics" section.
2. If a problem is found, repair as nec-
essary.
Was a problem found?
FUEL INJECTION SYSTEM TROUBLESHOOTING
Value(s) Yes
- Go to Step 2
- Go to Step 3
Go to OBD
System
-
Check
Go to OBD
System
-
Check
Go to OBD
System
-
Check
Go to OBD
System
-
Check
No
Go to OBD
System Check
Go to Visual/
Physical
Check
Go to Step 4
Go to Step 5
Go to Step 6
Go to Step 7
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