Re: Mercury Sport Jet 90 - losing power -- Hi Performance Boats Inc.

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Date Posted: 10:29:12 06/27/06 Tue
Author: Chris
Subject: Re: Mercury Sport Jet 90 - losing power
In reply to: Christina 's message, "Mercury Sport Jet 90 - losing power" on 07:14:14 06/21/06 Wed

Christina,

I have a 1996 Sportjet 120XR in a 14ft Sea Rayder. I can do about 37MPH tops. Not sure how off your speed really is since you have the 90HP.

Have you checked the impeller and wear ring? Look for dings on the impeller. The clearence between the impeller and the wear ring needs to be very tight. The engine timing could be off. I have a shop manual that (I think) covers your engine. It will give you a few more things to look at.

Regarding cutting out and inconsistant idle. Check fuel supply. The pickup out of the tank and make sure it's not clogged, the screen filter going into the fuel pump. Also the carb floats could be sticking.

You could try running a fuel system cleaner through the engine. Also you could try using a can of Mercury Power Tune in the engine.

Write me at chrisbb61@yahoo.com and I will email you the manual.

Hope I helped !, Chris

>We have a 94 jet boat w/90hp mercury sport jet. I
>have a couple issues:
>
>1) It seems that this boat is NOT going as fast as it
>should...it struggles to get to 30mph with only one
>person in it on a calm day in the bay. Seems to me
>that it should be able to go a lot better than that.
>Is there something that can be inhibiting the power?
>
>2) Speaking of power - end of last season - it started
>skipping at idle, inconsistantly. We just pulled it
>for the season, winterized it, and left it for then.
>This year we took the boat out for the 1st time and
>throttled up, it took off as it had last year...(again
>not as much power as I think it shoudl have - but
>consistent with the amount it had been putting out
>last year). After about 5 minutes we started to slow
>down....and we had NOT touched the throttle. Tried a
>few times - with same result, it just did not want to
>go anywhere.
>
>We're at a loss as we are not that familiar with this
>type of boat - and all marine mechanics are book too
>far out to look at this in time for us to be using it
>by 4th of july.
>
>HELP!!!!!!
>
>Could it be a fuel issue? (Also want to mention that
>the cutting out and inconsistent idle started shortly
>after filling it with fuel last year)
>
>Any input or suggestions or where to start looking
>would be appreciated.

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Replies:

[> Re: Mercury Sport Jet 90 - losing power -- Bob, 18:41:11 06/12/07 Tue

I had a 90hp sport jet and had problems with the throttle linkage. Had to readjust it to get my speed back.

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