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  1. #1
    my ski has thrust vectoring......does yours??? killcraft's Avatar
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    GPR pump problems

    ok so i have just replaced the drive shaft, wear ring, impeller and rebuilt the pump of my 2001 yamaha gp 1200R i got it back on the water and it will only do 30mph or so ...... until you unhook the pump out of the water (via waves or bouncing up and down on the ski) then she runs like a bat outta hell all the way to 70mph (GPS). ok so my thoughts are that i have put too much grease in the pump when i rebuilt it other than that theory i have no clue what it could be any thoughts??????


  2. #2
    my ski has thrust vectoring......does yours??? killcraft's Avatar
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    bump c'mon guys any ideas

  3. #3
    THE PLATE MAN JIM'S PERFORMANCE's Avatar
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    Quote Originally Posted by killcraft View Post
    ok so i have just replaced the drive shaft, wear ring, impeller and rebuilt the pump of my 2001 yamaha gp 1200R i got it back on the water and it will only do 30mph or so ...... until you unhook the pump out of the water (via waves or bouncing up and down on the ski) then she runs like a bat outta hell all the way to 70mph (GPS). ok so my thoughts are that i have put too much grease in the pump when i rebuilt it other than that theory i have no clue what it could be any thoughts??????
    it's not the grease, What pitch impeller did you put.

  4. #4

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    sounds like the power valves are hung in the open position. Check them for proper operation first.

  5. #5
    my ski has thrust vectoring......does yours??? killcraft's Avatar
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    as far as pitch goes the impeller is a remanded sbt stock impeller ill check the powervalves although i dont know why they would only kick in when i get the pump out of the water???

  6. #6
    Is it almost winter yet??? ProXR 440's Avatar
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    When you put the new prop on I'm sure you would of noticed if the pump didn't spin free. Just like mentioned above the motor isn't making power down low under load like it should so when it "unhooks" and free revs you're into the powerband and making enough power to pull the prop at that point. When you start/stop the motor do you hear the powervalve motor go through an open close cycle? If the motor feels real boggy it might be a carb issue also.

  7. #7

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    Quote Originally Posted by killcraft View Post
    ........ i got it back on the water and it will only do 30mph or so ...... until you unhook the pump out of the water (via waves or bouncing up and down on the ski) then she runs like a bat outta hell all the way to 70mph (GPS). .....


    The last time this happend to me was in 2001 when the catalytic converter broke apart and a piece of it got stock in the water box, plugging the exhaust. Whenever I bounced the boat around, it would move about inside and allow the exhaust gasses to escape, and the boat would "wake up".

    I assume that you replaced the cat con and checked all of your exhaust for missing parts......

  8. #8
    my ski has thrust vectoring......does yours??? killcraft's Avatar
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    well the prop spun smooth but not more than a few revolutions. yes i have pulled the stock cat and gone with a D plate my CAT didn't shell it was still in good shape when it was removed so no need to check for pieces of it. as far as powervalve noise i hear them move after cranking the engine i haven't paid attention to them after i shut down after the engine is running.

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