Motor surging above 3200 rpms
 

I have had a problem recently of my starboard motor surging at around 3200 rpms. This only happens under load (when I am running the boat).The boat will refuse to go past 3200-3500rpms. When the boat is in neutral it revs to 6200 rpms without a hiccup.
The engine in a 350 small block with mercury racing 700cfm carb.
So far I have checked distributor, replaced coil, rebuilt carb, checked fuel pressure from fuel pump..all this to no avail.

Any help appreciated as I running out of possibilities.

Re: Motor surging above 3200 rpms
 

Sounds like a mixture problem to me. It's proably running fat or the engine would be backfiring.

Re: Motor surging above 3200 rpms
 

Does your carb have the inline filter near the fitting from the fuesl line to the carb? I had an old donzi that did what you describe and my filters were plugged.

Re: Motor surging above 3200 rpms
 

could be air entering your fuel line or begining form of vapor lock

Re: Motor surging above 3200 rpms
 

Ttt

Re: Motor surging above 3200 rpms
 

Swap Carbs between motors & see if problem moves to other motor.

Re: Motor surging above 3200 rpms
 

I had a similar problem last year. Turned out my anti-siphon valve in the tank was bad. Hook up a portable tank to the fuel pump inlet. If problem goes away, that's probably the culprit.