Motor surges at WOT

[opaleski]

I've got a 1999 Mercury 20-25 hp on a Tracker 16 ft. Motor surges at 3/4 to wot so bad that it will slow down . Less throttle, it runs fine. New spark plugs didn't help, have also installed inline 10 micron filter. Same results with or without filter/water separator. Any idea's would be greatly appreciated.

[njterrier]

I've got a 1999 Mercury 20-25 hp on a Tracker 16 ft. Motor surges at 3/4 to wot so bad that it will slow down . Less throttle, it runs fine. New spark plugs didn't help, have also installed inline 10 micron filter. Same results with or without filter/water separator. Any idea's would be greatly appreciated.

[njterrier]

Is this fresh fuel?

Could there be a restriction in the fuel line?

Fuel pump?/primer bulb?

Sounds like a fuel starvation issue.

[Mal de Mer]

Is this fresh fuel?

Could there be a restriction in the fuel line?

Fuel pump?/primer bulb?

Sounds like a fuel starvation issue.

Either that or water/crap in the tank....Use a portable tank with fresh gas and see what happens....let her run a bit....if it works well , that means your onboard tank has water or contamination in it screwing up your engines and needs to de drained and flushed......if there is no improvement you may have something wrong with the engine (still may be fuel related if its carbed) or a bad squeeze bulb or anti-siphon valve not allowing full flow at WOT.

[opaleski]

Thanks for the response--I will check all of the above.