1999 7.4 MPI wont make power still!

[robert76]

I removed the injectors had them tested they passed, the boat falls flat at 3500 to 3800 rpm, wont come out of the water, asked my merc tech if it could be the fuel pump he said they usualy they work or dont, is this the case? Any ides?

 

[makomark]

I've seen a few that work fine up to a certain rpm and then won't supply enough fuel.

put a fuel pressure gauge on the rail and take it for a run. see what the gauge indicates when you hit the troublesome rpm. If it won't maintain the spec pressure, it may be time for another one.

 

[stoinkythepig]

Maybe a water shutter broke free and is clogging your exhaust. I had one in my gearcase that made the thing a real dog when I was trimmed all the way in.