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  1. #1

    Exclamation Help! Losing power while pushing full throttle

    My boat has a very well taken care of 1989 Nissan 90 hp motor.

    I've spent $2000 on rebuilding the carberator, electrical systems, fuel filters, spark plugs, etc. The machanic pretty much gave up at that point. Then I drained the gas tank and refilled several times (while adding HEAT and stabil) trying to run out any bad gas that's been left in the system. I've blown through the fuel tank's air hose, and it's not clogged. I can't seem to figure out what else could be wrong...

    Here's what happens every time I take my boat out:

    The engine starts up with no problems, I accelerate to about 3/4 of the power, and the boat planes out for about a minute. I then gradually start losing speed and the bow raises in the air, but the engine sounds like I'm still pushing full throttle and I'm actually only going a little faster than idle.

    Thanks for taking the time to read my post.

    Any suggestions would be greatly appreciated.

    Thank you,

    Larry
    Last edited by Larry123; 05-09-2010 at 12:56 AM.

  2. #2
    Join Date
    Mar 2010
    Location
    Buffalo, NY, USA
    Posts
    2,056

    Default Re: Help! Losing power while pushing full throttle

    You may have a spun prop hub.
    Paul
    Buffalo NY USA

  3. #3

    Default Re: Help! Losing power while pushing full throttle

    Hey Paul I took the propeller shaft out and it looks like the clutch and beval gear is hitting up at the top about 1/10 of an inch down, it is kind of rounded over towards the top and may be slipping. And it looks like the push rod isn't pushing it down far enough, would that maybe what could be causing it and if so what should I do?
    Last edited by Larry123; 05-10-2010 at 12:03 AM.

  4. #4
    Join Date
    Mar 2010
    Location
    Buffalo, NY, USA
    Posts
    2,056

    Default Re: Help! Losing power while pushing full throttle

    Larry,

    Review Elvin's parts catalog listing at http://www.internetoutboards.com/Par...2N21031-2).pdf so that we're on the same page.

    The push rod (when operated by the shift cam) activates fwd and rev, and I would be surprised, unless from extreme wear, if the travel was not correct. Wear on the clutch dog and the mating surfaces of the fwd and rev gears is typically caused by "gently" engaging gears. "Easing" into gear is not easy on the gears! The proper way to operate the shifter is to "snap" it into gear briskly.

    On the other hand, if the nut on the end of the driveshaft -- that fastens the pinion gear to the driveshaft -- is coming loose, that could cause all sorts of damage/wear issues.
    Paul
    Buffalo NY USA

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