Crownline 225 w/ Volvo penta 5.7L GXI & DuoProp. Boat started and ran great for 10mins through no wake zone. Just about on plane and motor cut out almost like it was starving for fuel, tried again and same results but then died. engine would not start. Let sit for about 10-15 mins and then tried again. Engine started and ran great again. Got up on plane and ran for about 1 mile at half throttle flawlessly and then same thing nearly died except it smelled gassy and could hear the intake sucking for air as it tried to stay running. The only way i could keep it running in any of these instances was to pump the throttle in neutral but did not run good at all. Backfiring and spitin and sputtering. Got towed in and about 15 mins later started right up and ran great for about 3-4 mins. Any ideas? I did replace the fuel/water seperator and ran with ear muffs. died after 10 mins of running.
Hello, welcome to JustAnswer.
Replace the electric fuel pump.
Why would it run fine only whe cooled down. Someone else suggested that but i assumed it was fine because every time i turned the key it pumped fuel. Could you explain a little. is it overheating?
Every time you turned the key you heard the pump motor spinning, that doesn't mean fuel was pumping. Most of the time, these electric fuel pumps never stop sounding like they are functioning, they spin, but the ability to create pressure is lost. Without pressure, they are useless in your boat.
They do get warm when in use. Then they loose pressure. It cools and works again until it gets heated up again. And each time, the length of time it works lessens.
You can see how this works with the use of a fuel pressure gauge hooked to the fuel rail schader valve. run the motor and watch the gauge it will likely remain steady as a rock, then suddenly drop in pressure. It only takes a little drop to decrease top end or under load performance (noticed by you as a lower engine rpm) as it gets worse the engine will bog down when trying to accellerate, start to idle bad and then not re start, until you get no starting at all. But the bump still spins away, it just isn't doing anything.