5.0 mpi mercruiser will not go above 3000 rpms at wot

[pfitz128]

I have a 2003 searay with a 5.0 mpi mercruiser, last year it began having issue with not getting on plane. After some time it would eventually go. This year I changes the plugs put it in the water started right up and it ran awesome. I parked it and an hour later of ran like crap again. I have checked fuel pressure 43-45 psi changed distributor and rotor, cleaned flame arrestor, and also had a seperate 6 gallon fuel tank hooked up still have the same problem




R

 

[Docksidemarineservices]

Hook up the fuel pressure gauge again and let it run a while. Raise the RPM's up and down and see if the pressure climbs.

 

[pfitz128]

Hook up the fuel pressure gauge again and let it run a while. Raise the RPM's up and down and see if the pressure climbs.

I had a boat mechanic with me, he hooked up the gauge and we took the boat out for a run, we ran it for about 15 minutes maybe longer,and the fuel pressure remained constant

 

[pfitz128]

I am at a stopping point until I know where to go next

 

[guyjg]

Disconnect each injector and carefully look for dirt or corrosion on the plugs and injectors. Still runs bad get it scanned for trouble codes.

 

[pfitz128]

I had it scanned and no codes popped could it be a bad or clogged injector with the fuel pressure being good. I mean it makes sense. If were clogged if might be the reason it runs good sometimes and bad sometimes