I have a 2001 Eliminator Daytona 26. I bought the boat without an engine. The boat had around 1100 hp before I bought it.

The boat came with a Cyborg trans that I had rebuilt by BAM.

The boat also came with a Stern Powr out drive with 1.32 gears.

The prop is a three blade cleaver style 24 pitch.

I bought a 540 that I had rebuilt and dynoed. It dynoed at 588hp with a 1050 Holley carb and 550hp with a 850 carb.

I installed the motor and ran it in the driveway and all was well. Idled great, in and out of gear the rpms didn't drop at all. I then took it to the water and that's when I noticed I had a problem.

When it's in the water as soon as I put it in drive or reverse the RPMs drop and the motor dies. Also I have the idle up around 1100-1200. I tried to throttle through the drop of RPMs but the motor back fires and dies.

I am hoping someone can give me some advice because I am at a loss.

Thanks!

Sounds exactly like my problem.i had 1 motor doing this.ended up being a bad lower gear set (missing teeth) in that drive.it went in and out of gear fine out of the water, in the water stopped dead in its tracks.it would only stay running giving it a decent amount of throttle.hopefully that's not you're issue.good luck

So I assume you replaced the lower gear and the problem was fixed? It went in and out of gear just fine after that?

How is your ignition timing?

Check the safety switch on the shifter? You could also run a hot wire to the dist and bypass the safety switch.

Try backing out the idle mixture screws 1/2 -3/4 turn each. Don't jack up the idle speed screw any more. Also, if that doesn't work, try blowing out the air bleeds in the carb with carb clean and the little red straw. Theres no load on the engine on the driveway when you put it in gear. Its loaded down in the water, with the prop turning. With increased load, it needs more air/fuel mix.

Cleaver style prop? How big ? I had identical problem at high altitude because of gearing and running rich. Got it properly tuned and put in prop aireators.

I'm not sure what the timing is but the dyno guy set it and ran perfect on the dyno.

Couple of things you have to keep in mind.

Dyno is not loading the engine at idle. With certain gears/prop combo, the engine can be loaded pretty hard at idle speed. Many times the guy tuning the carb will search for that "clean" idle, by turning the mixture screws in, and that works just fine in a car most of the time. Boats are different. Certain things can help this situation.

Proper carb tuning
More timing advance at idle (must make changes to ignition system via a different module, springs, or whatever your setup is, cant just turn distributor)
Heavy flywheel (lightweight flywheels can amplify the issue, as there isn't enough momentum to keep engine turning when shifting)
Prop aerator

If your near the boat, go turn your idle mix screws in, counting the number of turns until they seat...and report back to what you have.

Yeah it's a 19 spline 16" diameter.