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  1. #1

    Do I need a new Impeller?

    Hi guys. I have a 2009 FX SHO with 117 hours on it. When I pull the throttle all the way in at full throttle, it revs up all the way for a couple of seconds and doesnít move anywhere. After these couple of seconds it eventually hooks up and goes.

    Someone told me I might need a new impeller or is this normal from a ski?

  2. #2
    Erierunner's Avatar
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    Sounds like it's cavitating. The impeller and/or impeller area would probably be the culprit. Do you get top speed and or any vibration? It could be something small like a piece of rope or plastic grocery bag, wrapped around the shaft. Take a look from the intake grate and then the nozzle with a good flashlight to check the shaft and impeller. Impeller clearance to liner should be around .014-.024 inch. I wouldn't think the supercharger clutch slips then grabs and you said you get full rpms.

  3. #3
    TimeBandit's Avatar
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    Not being a grammar-cop but "ventilating" is probably more technically accurate. The pump sounds to be air-bound, and if you think of it in terms of a water-pump, it is simply un-primed for a sec or two. Then that 'hook-up' you feel and when the pump finally gets enough water to bite onto.
    ... damaged impeller, too much space around the wear ring, transom seal, pump tunnel cracked, intake grate / shoe needs sealing, foreign object lodged (rope/stick) .... aka all the above. There's no single default fix for poor hole-shot. It's a tiered approach, you will really need to get your eyes down there and verify all tolerances meet factory specification, and that you don't have a foreign object or damage present.

  4. #4
    Quote Originally Posted by Erierunner View Post
    Sounds like it's cavitating. The impeller and/or impeller area would probably be the culprit. Do you get top speed and or any vibration? It could be something small like a piece of rope or plastic grocery bag, wrapped around the shaft. Take a look from the intake grate and then the nozzle with a good flashlight to check the shaft and impeller. Impeller clearance to liner should be around .014-.024 inch. I wouldn't think the supercharger clutch slips then grabs and you said you get full rpms.
    Iíll take a look this weekend. I have no vibrations and get top speed. Also get full rpms so I donít think there is a slippage of the sc clutch.

  5. #5
    Quote Originally Posted by TimeBandit View Post
    Not being a grammar-cop but "ventilating" is probably more technically accurate. The pump sounds to be air-bound, and if you think of it in terms of a water-pump, it is simply un-primed for a sec or two. Then that 'hook-up' you feel and when the pump finally gets enough water to bite onto.
    ... damaged impeller, too much space around the wear ring, transom seal, pump tunnel cracked, intake grate / shoe needs sealing, foreign object lodged (rope/stick) .... aka all the above. There's no single default fix for poor hole-shot. It's a tiered approach, you will really need to get your eyes down there and verify all tolerances meet factory specification, and that you don't have a foreign object or damage present.
    Thank you. I’m going to take a look this weekend and find out if there is any foreign objects in there. I have a feeling it might need a new impeller after 10 years.

  6. #6
    WaterDR's Avatar
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    Do this....

    Get a bright light and get a good look at the impeller through the jet nozzle. Look for signs of damage. Then, take the light and have someone shine it up through the grate. Then look through the nozzle. You should see an even amount of light around the edges of the impeller and you should barely be able to see the light.

    Then measure the size of the gap between the impeller and the housing. The measurement will be in millimeters. You will need a cheap tool for doint that...sort of like a spark plug gap tester.

    this is what you need:

    https://www.google.com/shopping/prod...E,gclsrc:aw.ds


    There is a spec on the gap. I don’t recall what it is but yamaha service can tell you. If you are well beyond spec, then that’s the issue.

    You will need to see if it’s a wear ring issue or a prop. Could be both. If it’s fine then it’s anothwr issue.

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  8. #7
    Click avatar for tech links/info K447's Avatar
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    The Impeller blade to wear ring gap is measured using a feeler gauge.

    Attached Thumbnails Attached Thumbnails Click image for larger version. 

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  10. #8
    butterbean_29512's Avatar
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    Clearance spec is .010-.020, service limit of .024. (Thousandths of an jnch)


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