SERVICE MANUAL NUMBER 23
FUEL INJECTION SYSTEM TROUBLESHOOTING
Page 5D-15
90-861326--1 MARCH 1999
Lack of Power, Sluggish or Spongy Symptom (Continued)
12
1. Check for intermittent opens or short
to grounds in the ECT sensor, MAP
sensor and TP sensor circuits. Also
check or throttle linkage sticking,
binding or worn.
2. An intermittent failure may not store
a DTC.
3. If a problem is found, repair as
necessary.
Was a problem found?
-
Go to
OBD
System
Check
Go to
Step 13
13
1. Check ECM grounds for being
clean, tight and in their proper
locations.
2. If a problem is found, repair as
necessary.
Was a problem found?
-
Go to
OBD
System
Check
Go to
Step 14
14
1. Check for engine going into rpm
reduction mode.
2. If a problem is found, repair as
necessary.
Was a problem found?
-
Not
Applicable
to
MerCruiser
EFI or MPI
Go to
Step 15
15
1. Check diagnostic test CKT 451 for
being shorted to ground. This will
cause the rpm to be lowered.
2. If a problem is found, repair as
necessary.
Was a problem found?
-
Go to
OBD
System
Check
Go to
Step 16
16
1. Check or proper alternator voltage
output.
2. The voltage should be between
specified values.
3. If a problem is found, repair as
necessary.
Was a problem found?
11-16
Volts
Go to
OBD
System
Check
Go to
Step 17
17
1. Check for the following Engine
Mechanical problems:
• Low compression.
• Leaking cylinder head gaskets.
• Worn or incorrect camshaft.
• Proper valve timing/valve train prob-
lem.
• Restricted exhaust system.
2. If a problem is found, repair as
necessary.
Was a problem found?
-
Go to
OBD
System
Check
Go to
Step 18
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