SERVICE MANUAL NUMBER 24
TROUBLESHOOTING
Engine Acceleration Is Poor
Cause
Special Information
Also refer to “Poor Boat Performance”
Idle mixture screws improperly adjusted
Incorrect ignition timing
Incorrect distributor or amplifier advance
curve
Refer to SECTION 4B
Check for stream of raw fuel from acceler-
ator pump discharge nozzle, when open-
ing throttle with engine shut off
Accelerator pump
Distributor cap or rotor
Vacuum leak
Dirty or cracked
Intake manifold or carburetor base
Fouled, burned; wrong heat range;
cracked porcelain
Spark plugs
Float adjustment
Dirty carburetor
Low compression
Troubleshooting with Vacuum Gauge
Reading
Cause
Steady reading between 15-21 inches at
idle rpm
Normal
Extremely low reading, but steady at idle
rpm
Vacuum leak, incorrect timing, underpow-
ered boat, faulty boat bottom
Fluctuates between high and low at idle
rpm
Blown head gasket between two adjacent
cylinders
Fluctuates 4 or 5 inches very slowly at idle Carburetor needs adjustment, spark plug
rpm
gap too narrow, valves are sticking
Fluctuates rapidly at idle, steadies as rpm
is increased
Valve guides are worn
Continuously fluctuates between low and
normal reading at regular intervals at idle
rpm
Burned or leaking valve
Index
90-861327--1
OCTOBER 1999
Page 1C-17
| 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 |
(1 votes, average: 4 out of 4)
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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