350 MPI w/ Bravo III - Dramatic power drop! Please help!

[WaterNovice]

I just bought my first boat, 2003 used 220 Sundeck with 160 hrs, and when we did the water test and for the first couple trips out it was running like a dream (cruising @40mph and maxing out with 5 adults @50mph).

Then about two weeks after taking ownership the old girl seems to have a serious issue. From idle to 2200 rpm she seems to be ok; but then stays there... and stays there for a LONG time (>5 min). The engine creeps ever so slowly to around 3000 rpm (when when the boat begins to plane) and then gets up to 4000 rpm pretty quickly (cruising at around 35mpg). I have not been able to get it above 40mph since then either... Any ideas, hints or clues? Id rather not spend an entire weekend and $$$ to take the boat out of water so a mechanic can tell me its a switch...

Thanks!

 

[tbirdvet]

My last boat was a 22' with your engine. You should get to around 4600-4800 RPM with the correct prop. When was the filter in cool fuel module last changed? You may have some water in the fuel and changing the filter may get rid of this. I assume you have added new fuel since purchase?

 

[MasterFab]

I would not be at all surprised if it was as simple as a clogged fuel filter, especially if the boat sat for a while before you bought it. Since you did not specify that the boat was misfiring, only that it won't reach proper RPM, we can likely rule out an electrical or ignition problem. A mis-adjusted throttle cable would also do it. Is the throttle stiff? Did anyone make any adjustments to it?

Try to provide any more information you can, and someone on this forum will be able to point you in the right direction. There's no doubt that whatever it is, it happened to one of us before...

Dale

 

[mainstream]

I had a similar problem at 100 hr on my new boat it turned out to be a set of bad plugs it was a 2009 left over and I think it just sat for a while and fowled the plugs also are taking care of the ethanol with the gas treatment good luck

 

[SeaRide]

If the boat has literally not been out of the water since you bought it and you are in in brackish water without bottom paint, you probably have enough crud/marine growth to seriously hamper performance. You may need to have the hull and drive cleaned.

 

[quailrunner]

I'd go for the first explanation; I've seen it on friend's boats several times. Boats need tune-ups just like cars (well, not *exactly* like cars). New plugs and changing the filters, plus a shot at a fuel additive to dry out water, will likely help. It's the first thing our mechanic recommends in these situations unless there's an obvious additional symptom.

 

[WaterNovice]

Thanks Everyone! I will replace the plugs and filters (fuel and water separator) and post results...

 

[Searay Jim]

I would agree with the filters first. It's not exactly, but very much like fuel starvation. And it seems to come on quick in boats.

 

[spfortjohn]

With the new corn juice fuels I would change the fuel filters at 50 hours