Boat top speed 10 mph!

[dogbert]

Usually when I see an engine problem I look at Spark, Fuel, and Air. Pull the air filter off and see if that helps at all.

But honestly this issue reminds me of the time I left the choke on, on my dirt bike. It idled normal, but ran like crap when I gave it any gas, changed my plug but it still continued...a few seconds later saw the choke still one. But my thoughts are your engine is EFI, so all that would be electronically controlled.

With that in mind, one thing to do would be to clean the flame arrestor on top of the engine. I know when I took mine off last year, it was pretty dirty. What made me do it was that i could smell gas every time i was coming off plane, which made me believe I was running rich. That and it used to make a whistling noise at WOT.

[goboardgo]

OK, Today I put the boat in the water with the pressure gauge attached to the fuel rail. I'm not sure what my pressure is supposed be (I'm thinking it's supposed to be around 38 - 42 PSI) I have 30 PSI at idle and it drops to 24 PSI under load. That sounds low, is it?

[dogbert]

OK, Today I put the boat in the water with the pressure gauge attached to the fuel rail. I'm not sure what my pressure is supposed be (I'm thinking it's supposed to be around 38 - 42 PSI) I have 30 PSI at idle and it drops to 24 PSI under load. That sounds low, is it?

I think so, someone posted what the pressure ought to be here somewhere. Whatever it is, it shouldn't drop under load.

[urbanstd]

I have seen marine fuel hose deteriorate internally that will cause problems with fuel pump, siphon valves, filters etc. The ethanol added to gasoline will make this problem worse. I don't know the layout of your fuel system, can you disconnect the fuel hose close to the tank and blow back into the tank with low pressure air? This would clear fuel tank pick up (there was reports of some boats with contaminants plugging or partially obstructing the pick up. I would work from the tank to the fuel pump trying to make sure fuel flow is not obstructed. If the hose and piping are fine then I would change the fuel pump. Lately in our area of NC there has been a bunch of cars and trucks that have suffered fuel pump failures (My Father in law runs a towing company) do to ethanol and the baggage that comes with it. Good Luck