Boat Slows Downs at WOT then speeds right back up

[MIKESANDO]

I have a 1996 fourwinns 4.3 and when I am at WOT (or on plane) I can slightly feel it slowing down and then it will speed back up. the engine will not stumble or make any noise. It has been doing it for the last 5 times out. I have checked all gas lines and cleaned the carb as best as I could. Could it be electrical? Prop is fine and tried reading other post but no luck? Could it be my main ground to my battery, cause when starting with a new battery it will pause a sec then crank right up. Please help​

 

[Scott Danforth]

if its surging, I would look at fuel system - most likely the carb, however could also be plugged anti siphon or fuel/water filter.

 

[MikDee]

Your not peddling fast enough :lol:
I agree with Scott, check your fuel tank pickup screen at the bottom, antisiphon valve, and fuel filter for debri.

 

[wellcraft-classic210]

Sounds like you have a limited fuel supply--- delivery issue.

Have you replaced the fuel filter ?

Another possibility is debris lodging in your anti siphon check valve ( barbed fitting leaving the fuel tank )

 

[Maclin]

You can feel the boat slow down but the engine tone does not change and the RPM stays the same?

 

[MIKESANDO]

Yes that is correct it will slow down and NO change at all to the motor or RPM, and when you are standing up you can feel it a lot more (obviously).

 

[MIKESANDO]

And also the fuel filter was replaced at the beginning of last summer.

 

[Bondo]

And also the fuel filter was replaced at the beginning of last summer.

Ayuh,.... So take it off, 'n dump it into a clear container, 'n look for Crud, 'n water,....

 

[GA_Boater]

This is being merged with your other topic.

 

[nateccnn]

If the RPM stays the same and engine sounds the same can we assume the prop is still spinning same RPM too? If so it has to be something dragging the hull of the boat or debris on the prop or cavitation of some sort. Are you watching an RPM gauge to verify the RPMs don't change or are you solely basing this comment on the sound of the engine?

 

[MikDee]

If this was the Great South Bay off Long Island, I'd say you picked up some spaghetti weed! Seaweed, that is! It is a constant problem there, first you hafta slow down, then put it in reverse, rev it just a little, then back in forward to get it off the prop, then you're good to go again. one of the great Joys of the Great South Bay