I have a 2006 Supra 20ssv inboard with a 325 assault engine and around 250 hours. Mid season last summer I was pulling a rider and crossed another huge wake at speed, almost immediately the boat pops and sputter with half throttle or more, we had to limp back to the dock because the boat would not get on plane . Now ONLY after 2 or so hours on the lake the boat will run bad and we'll have to idle back to the dock. The boat will run perfect, full throttle, pull hard etc while in gear or disengaged. After 2 hours the boat will not rev past 3K while in gear or in neutral, it will fall on its face like its entering limp mode, it will backfire if you keep giving it throttle while its lugging. Oil pressure and temp gauges work and are within spec during the sputtering.

I've replaced the fuel, fuel filter, added stabilizers, isodeet, seafoam, etc, changed and gapped the spark plugs, checked fuel and fuel pressure at the Schrader valve and it was good, looked for exhaust leaks or blockages anywhere in the system, the propeller is good, all throttle linkages are good, there is no distributor cap.


I'm at a loss of what to do. I might try a new fuel pump but I dont think it is the problem. The fule pressure is 60psi constant but I didnt get to check the pressure while it was lugging down unfortunately.

I'm not sure if it is sensor or electrical related due to the original impact, but I know that it is temperature related and most likely fuel related.

Sorry for the long read, I wanted to be thorough on the first post as I have researched this forum and others extensively.

Thanks for any help and input, its greatly appreciated.

P.S. I'll gladly Paypal $20 to whoever can tell me the problem or steer me in the right direction if its not the fuel pump