5.0 Mercruiser MPI

[ronmhjr]

We have a 2007 Sunesta 214 with 5.0 MPI that starts fine, idles and runs at low speed but when I put the throttle down it stays around 4k rpm but doesn't really go (10 mph max). It takes a while (me thinking it needs to warm up) and then runs fine. I let it run like that until a point you can hear the engine gaining power and losing it and then it seems to clear out and it runs normal. It has been a constant issue for the past two summer but with it being new to me, thought is was normal. No other issues with running until you stop for an extended period and the issue starts again. It really doesn't want to go until it's been run for several minutes. When in neutral I can rev the engine with no issues.

 

[bondo]

Ayuh,..... Possibly a fuel restriction, but you need to scan it with a diagnostics computer,....

 

[sandkicker]

4K RPM and 10mph is a suspicious situation on a 21 ft boat... Prop hub slip??? Coupler???

 

[o2batsea]

Agreed. 4K you should be nearing top speed. Something is broken bigly.