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  1. #1

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    Stx-12f low power

    Ok hey guys..

    i bought a 2005 stx-12f that wouldnt go above 30mph for very cheap. I rode it when i got it and it would do only like 30mph and it took forever to get there.. I took it home and did a compression check it was 210, 190, 180, 140.. I took the engine out and one piston was cracked on the top.. I replaced the piston and rings on all cylinders and had the cylinder checked. I also had them check the head and 7 of the 8 intake valves were highly corroded. So I had all new intake valves installed. I got it all back together and it runs very good out of water. I tested it out today and its a few mph faster but just doesnt feel like it has much more power at all and wont rev above 5k. So i did another compression check and there all 205-210. So thats perfect. Any suggestions?

    Thanks Bryan


  2. #2
    My name is Sean and I am addicted to STXs smokeysevin's Avatar
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    Re: Stx-12f low power

    Check the fuel pressure and the jet pump bearings. Also look for leaks in the exhaust couplers.

    Sean

  3. #3

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    I tested fuel pressure today it was at 22psi at idle. I replaced the pump it only went up to 30. Im going to order a new regulator. Im assuming thats it! I already rebuilt the jetdrive. Bryan

  4. #4
    My name is Sean and I am addicted to STXs smokeysevin's Avatar
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    yep, replace the regulator and check the filter, it should be 41-43 psi

    Sean

  5. #5
    Pain is fear leaving your body.... rlovebk's Avatar
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    Look at the last 2 numbers on your ECU and let us know what they are. Don't want this to happen again.
    12F should be 235 psi compression but above 200 is good. Probably your gauge/test procedure. As long as they are within 10% of eachother you should be good.

  6. #6

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    Ya ill check the ecu tonight. I did the adjustable fuel regulator w/ gauge.. It runs WAY better.. Only thing is it only goes about 40mph and still wont go over 5k in the water..

  7. #7
    new plugs ?

  8. #8

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    Ya has ngk iridiums less than a hour on them

  9. #9

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    Btw i did another comp check with a snap-on gauge were all 230-235

  10. #10
    pull the glovebox then the fuel cell assembly, is the sock restricted ? post a pic, while out power up the fuel pump, is it noisy and rattling or smooth and quite ?

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