MerCruiser 5.7L (5.7) Runs Rough at Idle
Question
My MerCruiser 5.7-liter 350 V8 engine runs rough. My MerCruiser motor is a GM .5.7 L competition 4 barrel. What would cause the motor to operate irregular or run poorly while disconnected from a heavy load or out of gear?
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Troubleshooting
3 weeks
2021-02-13T22:51:00+00:00
2021-02-13T22:51:00+00:00 0 Answers
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Answers ( 3 )
You mentioned that the MerCruiser is running poorly and that it idles rough, but you didn’t give me specifics. A rough idle can have different causes as compare to an engine that runs poorly.
What are the exact symptoms? Knowing what the exact symptom is can make finding a solution much easier. Here are a list of things you should check on your MerCruiser 5.7 L engine under different conditions.
Carburetor malfunctions
Engine runs poorly at idle
Rough Idle
Idle RPM too low
Idle mixture screws need adjustment
Idle passages dirty
Throttle valve not closing
Engine flooding
Vacuum leak
Throttle body heat passages are blocked
Engine Surges
Main metering jets
Leaking gaskets
Float adjustment
Saturated float
Power piston or valve
Throttle valves
Lack of power or lot top speed
Leaking gaskets
Main metering jets
Float adjustment
Power piston or valve
Poor cold engine operating
Engine flooding
Automatic choke
Idle RPM too low
Idle mixture screws
Throttle valves
Engine stalls
Idle RPM too low
Accelerator pump
Leaking gaskets
Automatic choke
Dirt in carburetor
Engine flooding
Idle mixture screws
My Mercruiser 350 engine is accelerating poorly. What would be the cause of that?
Carburetor malfunctions
If there is hesitation or acceleration flatness check the carburetor for malfunctions.
Engine acceleration is poor
These are more general procedures for troubleshooting acceleration problems.