Mercruiser RPM problem

dannylee

Recruit
Joined
May 10, 2009
Messages
2
I am having a problem diagnosing an rpm problem in a 1998 mercruiser 350mpi. The portside engine maxes out at 3200 rpms while the starboard engine continues to accelerate. I have changed the fuel filters, swapped the map sensors and coolant temp sensors. I also swapped the computers to see if the problem switched from port to starboard. Any help with diagnosing this would be greatly appreciated.
 

QC

Supreme Mariner
Joined
Mar 22, 2005
Messages
22,783
Re: Mercruiser RPM problem

Same props? Same condition? History? Ever been right?
 

dannylee

Recruit
Joined
May 10, 2009
Messages
2
Re: Mercruiser RPM problem

The props are the same on the port and starboard sides. This problem was not occurring during the season last year. New exhaust mainfolds were put on during the winter. When it was put back in the water this year the problem was there.
 

QC

Supreme Mariner
Joined
Mar 22, 2005
Messages
22,783
Re: Mercruiser RPM problem

Take a look at the Adults Only sticky at the top of this section. #12 is relative. Despite the length, all areas need to be considered. Proper troubleshooting requires it, although the manifold swap may indicate some possibilities that others may comment on. You can obviously eliminate a few things by the swaps you've already done.
 
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