Need help with 88 johnson spl on 24 ft pontoon boat

[nitro901]

has 13 3/4 x 15 prop----engine mn--J88MSLCUS--S#---7484182-----WATER SEEMS TO BE PUSHING AWAY FROM MOTOR BAD---MOTORS STILL PUMPING WATER BUT IT SEEMS LIKE IT CAVITATING BAD----WAS TOLD I NEED TO CHANGE PROPS AND PUT A HYDRO FOIL ON IT---ALSO WAS TOLD IT THE ENGINE COULD BE A SHORT SHAFT--I DONT KNOW --IT FITS BELOW THE PONTOONS WELL SO ITS GOING DEEP ENOUGH IN THE WATER FOR SURE---IT HAS TILT AND TRIM SO I CAN ADJUST---ITS AS LOW AS IT CVAN GO ON BACK OF PONTOON--ANY ADVICE ON THE PROP--HYDROFOIL OR ENGINE INFORMATION WOULD BE APPRECIATED---

 

[hidef]

Re: Need help with 88 johnson spl on 24 ft pontoon boat

First off please don't use all caps it is the equivalent of yelling and is not considered to be polite. The first question I have for you is the cavitation plate below the bottom of the pontoons? The outboard will pickup water even when the prop is cavitating. Has the prop been damaged that can cause issues. Do you have a tach? If so what are your RPMs? Does it seem like the outboard is over revving?

 

[aldennis]

Re: Need help with 88 johnson spl on 24 ft pontoon boat

Check for water in pontoons/how far are they in water. Had same problem till I drained about 25 Gals of water from toons. Seems ok now. Strange solution and may not be your problem.

Al

 

[nitro901]

Re: Need help with 88 johnson spl on 24 ft pontoon boat

pontoons not leaking---no water in them

 

[Daviet]

Re: Need help with 88 johnson spl on 24 ft pontoon boat

Is the cavation plate lower than the bottom of the pontoon?

 

[nitro901]

Re: Need help with 88 johnson spl on 24 ft pontoon boat

no its high

 

[Daviet]

Re: Need help with 88 johnson spl on 24 ft pontoon boat

If the engine is mounted to high it will suck air and cavatiate. The prop needs to be completely under water at all times.
Hold a board across the bottom of the pontoons and check the level of the cavation plate, has to be below the board.

 

[nitro901]

Re: Need help with 88 johnson spl on 24 ft pontoon boat

ill post picture of motor mounted on boat sunday