1997 5.7L GL Loosing Power @ WOT

[Verlin]

1997 Four Winns 5.7L GL losing power at WOT and has shut completely down after running for 1/2 hour or so. Typically it just drops about 5MPH and loses RPMs. When it does this it also bogs when hitting rough waters/waves. Runs real well at idle and mid range.

I have replaced all the gas, spark plugs and gas filter.

Not sure if it has anything to do with it but I back washed the motor a few weeks prior to this symptom starting.

 

[Don S]

Re: 1997 5.7L GL Loosing Power @ WOT

Not sure if it has anything to do with it but I back washed the motor a few weeks prior to this symptom starting.

Explain "I back washed the motor", never heard of it before.

Go for a run on a nice day, then when it starts slowing down or stops, remove the gas cap and see if it speeds up or will then start. Acting like lack of fuel.

 

[Verlin]

Re: 1997 5.7L GL Loosing Power @ WOT

What I mean by "back washed" is I stopped quickly, and cut the motor. It had a bit of a spark knock and my wave hit the back of the boat filling the exhaust and the cylinders with water. I quickly pulled all the plugs, cracked the motor to flush the water out of the cylinders, replaced the plugs and fired it back up. Ran it for a while then replaced the oil a few days later to be safe even though I didn't see any evidence of water in the oil.

 

[Verlin]

Re: 1997 5.7L GL Loosing Power @ WOT

Sorry Don, that should be "cranked" the motor not "cracked".

 

[Don S]

Re: 1997 5.7L GL Loosing Power @ WOT

Can't see that being a problem since it runs ok at times.
Still sounds like a supply problem to the pump.
Here is some further testing you should try.

HOW TO: Testing your boats fuel system.?/ 283269

 

[Verlin]

Re: 1997 5.7L GL Loosing Power @ WOT

Thanks, I will check this out and reply back in a few days.

 

[Verlin]

Re: 1997 5.7L GL Loosing Power @ WOT

Problem solved! Backflow preventer on the top of the gas tank had carpet like stands clogging it up. Removed the strands, worked it to ensure the ball was moving freely, reassembled and she is running like a top!