Boat not revving past 4000 rpm

[walleye seeker]

I have a 2003 mercruiser 350 mag mpi Motor sems to be running fine but it wont rev past about 4000 rpm

Boat used to max right out at 5000 rpm 43mph now 4000 rpm 34 mph

It also seams to be lagging power the boat weights 5000 lbs and use to launch out of the water now it seams to be laboring and has to build up power

same prop the only thing i have changed lately is the shutters i even tore it back apart and they are installed correct

am i hitting some sort of limp mode or rev limiter

 

[Burtonair01]

Re: Boat not revving past 4000 rpm

Do you keep you're boat slipped? Could be growth buildup which slows you down big time. I'm having the same problem right now, pulling the boat out after the holiday weekend to clean then put back in.

 

[walleye seeker]

Re: Boat not revving past 4000 rpm

Do you keep you're boat slipped? Could be growth buildup which slows you down big time. I'm having the same problem right now, pulling the boat out after the holiday weekend to clean then put back in.

No i think the guardian system has reduced my power to about 80% but im not getting any alarms at all. and it seams to run smooth no missing or nothing just no power and hits rev limiter at 4000 rpm should be 5200 rpm

 

[Burtonair01]

Re: Boat not revving past 4000 rpm

That sucks, good luck with it, wished I was more help.