1999 nissan 90 hp really low rpm

[kirk70]

i have this motor on a 24ft astro pontoon with a 11 pitch 3 blade prop. the highest rpm i can reach is 3200. if i really trim it up (almost out of the water) it will hit 4000, but not grabbing any water. i started at a 15 pitch and have steadily gone down. i know this is not a speed boat, but i also feel like 3200 is way too low. my friends' pontoons of the same size turn over 5000. the motor sounds great and runs like a charm. my buddy has a 24 footer with a 70 hp nissan and it just leaves me behind. the only thing i can really notice is that my moter does not sit low enuff in the water. could that be a problem. ps. i am motor illiterate

 

[TOHATSU GURU]

Re: 1999 nissan 90 hp really low rpm

Something else is wrong. Have you checked the pontoons for water?

 

[kirk70]

Re: 1999 nissan 90 hp really low rpm

now that you mention it, we did hear some sloshing for the first time this past weekend and some bubbles from the back of one of the pontoons, but the pontoons sit really high in the water and always have. am i correct in thinking that the rpms should be alot higher? would it take much water to really slow it down?

 

[TOHATSU GURU]

Re: 1999 nissan 90 hp really low rpm

A lot of different things can cause an RPM loss, but you would be surprised how many boats, with this problem, are just filled with water.

 

[kirk70]

Re: 1999 nissan 90 hp really low rpm

get this, the pontoons do not have drain plugs on the back. they have them on THE TOP of the pontoons. i guess you have to siphon the excess water out? if it is not the water do you have any other ideas?

 

[TOHATSU GURU]

Re: 1999 nissan 90 hp really low rpm

Carbs, ignition and compression.