FUEL INJECTION SYSTEM TROUBLESHOOTING
SERVICE MANUAL NUMBER 24
Poor Fuel Economy Symptom
Step
Action
Yes
No
PROCEED TO
Definition: Fuel economy is noticeably lower than expected. Also, economy is
noticeably lower than it was on this engine at one time.
Was the “On-Board Diagnostic” (OBD)
System Check performed?
1
Step 2
Step 3
OBD
Was visual/physical check performed?
Visual/ Physical
Check
2
3
1.
.Check operators driving habits. Are
excessively heavy loads being carried? Is
operator accelerating too much, too often?
Was a problem found?
System normal
Step 4
Step 5
1.
Check flame arrestor for dirt or being
plugged.
4
5
6
2.
Check for fuel leaks.
Was a problem found?
1.
•
Check for proper fuel pressure.
Refer to Table A-4 in “General System
Diagnostics” section.
Was fuel pressure 30 psi for EFI or 3–7 psi
for carbureted engines?
Step 6
Step 7
1.
Check for proper operation of Ignition Con-
trol (IC) circuit and the Knock Sensor (KS)
circuit.
Was a problem found?
1.
Remove spark plugs, check for wet plugs,
cracks, wear, improper gap, burned elec-
trodes or heavy deposits.
•
Refer to Distributor Ignition System.
7
NOTE: If spark plugs are gas or oil fouled, the
cause of the fouling must be determined
before replacing the spark plugs.
Were spark plugs damaged?
Step 8
1.
Visual (physically) check vacuum hoses
for splits, kinks and improper connections
and routing.
8
9
Was a repair required?
Check engine compression for being low.
Was a problem found?
Step 9
1.
OBD
Step 10
Index
Page 5F-20
90-861327--1 OCTOBER 1999
| Categories | Mercury MerCruiser Manuals |
|---|---|
| Tags | Mercury MerCruiser 305 CID, Mercury MerCruiser 350 CID |
| Model Year | 1998, 1999, 2000, 2001 |
| Download File |
|
| Document File Type | |
| Copyright | Attribution Non-commercial |
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Marine readers have rated Mercury MerCruiser Engines Service Manual Number 24 GM V-8 305 CID 350 CID 4.0 out of 4.0 based on 1 product reviews. Great performance engine.
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