Engine Stall/ Weird Revving at higher throttle
 

I just dropped my first boat ever in for the first time today. Its a Hydrodyne Grandsport with the PCM proboss gt40 engine. Whenever i throttle up passed about 3/4 it acts like its going to stall then revs back up and does this repeatedly unless i lay off the throttle a bit.. it is fine at all speeds needed for wakeboarding. Any help would be appreciated i'm not mechanically inclined.

Your probably hitting the rev limiter. Not sure about the GT40 but my Mercruiser has a rev limiter set that will do the same thing at WOT. In laymens term it's your engine telling you your pushing it too hard/fast.

gt40 with pro-tec ignition? (4 coil packs located above flywheel, 2 plug wires per coil w/ round flat capped black distributor)

Sounds fuel related.Could be starving for fuel.I would check fuel filter and fuel pump.

This is what we thought it might be... are these pretty easy to change out on a direct drive inboard? I dont have a rev limiter i dont think, and i believe this was happening around lower RPMs like 2500 but i'm taking it out at noon today so i will get some more information then.

If it's your fuel pump,they are usually in the tank.If it's your fuel filter,you usually have two.One is in the fuel line coming off the tank under the floor.The other is mounted to the side of the motor on a PCM. You could take a fuel pressure reading at the motor and do a fuel flow test to see if there's a restriction in one of the filters.

Are these symptoms i have typical of a fuel problem. It only does it at high throttle.. if i ease into a higher throttle it doesnt seem to occur.

It is possible to have coil breakdown at a higher RPM and engine load,but you would also feel it on a holeshot. Engine load will expose a bad coil.Where as easing into the throttle won't. It's similar to the fuel starvation problem,but that usually happens at higher rpm's because a weak fuel pump or clogged filter can't keep up with demands.

What year is your boat? How many hours on it?

Its a 1995 with 555 hours... i talked with the previous owner and he said he had the fuel pump and filters changed 5-6 years ago... said i may have a lose battery terminal b/c this had happened to him before and that was it.

That was the edge years between carbs and fuel injection.Which is it?

Its EFI

I would still suspect fuel problem.

ended up being the positive terminal on the battery not being tight enough... took it out for 4 hours today with no issues thanks everyone.