Engine Acceleration Is Poor
Cause
Special Instructions
Also refer to “Poor Boat Performance”
Idle mixture screws
Incorrect ignition timing
Incorrect distributor or amplifier advance curve
Refer to Section 4B
Check for stream of raw fuel from accelerator
pump discharge nozzle, when opening throttle
with engine shut off
Accelerator pump
Cracked or dirty distributor cap or rotor
Vacuum leak
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
Vacuum leak; incorrect timing; underpowered
boat; faulty boat bottom
Extremely low reading, but steady at idle RPM
Fluctuates between high and low at idle RPM
Fluctuates 4 or 5 inches very slowly at idle RPM
Blown head gasket between two adjacent
cylinders
Carburetor needs adjustment; spark plug gap
too narrow; valves are sticking
Fluctuates rapidly at idle, steadies as RPM is
increased
Valve guides are worn
Burned or leaking valve
Continuously fluctuates between low and normal
reading at regular intervals at idle RPM
Index
90-823224--2 796
TROUBLESHOOTING - 1C-17
| Categories | Mercury MerCruiser Manuals |
|---|---|
| Tags | Mercury MerCruiser 454 CID, Mercury MerCruiser 502 CID |
| Model Year | 1993, 1994, 1995, 1996, 1997 |
| Download File |
|
| Document File Type | |
| Copyright | Attribution Non-commercial |
(4 votes, average: 4.5 out of 5)
Marine readers have rated 1993 1997 Mercury-MerCruiser GM V8 454 CID 7.4L and 502 CID 8.2L Marine Engines Service Manual Number 16 4.5 out of 5.0 based on 4 product reviews. Hugely helpful service manual! Perfect. Thank you!
Manuals are all Important for Technician
This book is invaluable if you do your own repairs. Great book.
Could not find a copy until a search brought me here.
Excellent print.
Thank you