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  1. #1

    Need Help! 94 SL750 Power issues

    Hi all,
    I have a 94 SL750 that doesn't seem to have the "balls" it should. This machine was thrown in on a deal with my SL900 and a trailer so I don't know if this is normal or not, but I used to have a 93 Seadoo XP650 that would walk all over this. On the lake I can only get the thing up to 25-30MPH (about 5000 RPM) if I am lucky and if I hold it WOT it will very slowly climb from there. Also, it will sometimes if I am cruising will slowly loose Speed/RPM at WOT then slowly come back. I have already rebuilt the Carbs, Removed the Autocock, Upgraded to a triple outlet fuel pump, changed the plugs, drained the tank, upgraded the tank venting, Checked compression (115-120 on all holes) and rebuild the jet pump (Bearings/Seal, impeller and wear ring). I am now at a loss on what to do next.

    Any ideas or help would be much appreciated.

    Thanks,
    Doug


  2. #2
    Click avatar for tech links/info, donation request K447's Avatar
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    Welcome

    It seems like you been reading up and doing the suggested maintenance. Good stuff.

    Have you opened the electrical box? Any corrosion or moisture, damaged wires?

    Which spark plugs are installed?

    Did you trim back the spark plug wires about 1/4" at the plug boots and screw the boots back on snugly?

  3. #3
    I have had the box open and looks clean and dry in there. I have not yet tried to trim the plug wires yet.

  4. #4
    Ok So I trimmed the plug wires back 1/4" to clean looking core and still no change. Also, I am running the plugs the book recommends BPR7ES if I recall correctly

  5. #5
    BlueFishCrisis's Avatar
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    Did you take a look at the reeds when you were building the carbs? What does your piston wash look like? Have you done any plug chops? What in line fuel filters are you running, if any? Have you tested / rebuilt the fuel shut off switch. Do you have the return restrictor installed in the return line. Have you double checked that the fuel lines are correctly connected to the fuel sender? Have you ohm tested the stator?

    Ski should top out around 45 MPH at 6250 RPM, and get there pretty quick....

  6. #6
    I didn't check the reed because when reeds are not closing correctly usually you will get very poor idle or no idle at all and that is not my case. I have not check the piston wash yet, but I know the compression is good in all three holes. As stated in the last post I cut back the plug wire (Assuming that's what you mean by "plug chop"?) I have verified routing and connections on all fuel lines and there is really good fuel flow though the system and when I have checked the fuel bowl is always full. The restrictor is installed in the fuel return line as specified. I have not tested the stator, but could that really cause this kind of issues? What confuses me is it starts and idles perfect and sounds great.

  7. #7
    Well tomorrow I will finally get around to testing the stator and coil's. My question for you guys is do you think my issue could be caused by the stator or CDI? If so, I'm not to clear on the digital vs analog or what year/size cdi will fit.

  8. #8
    BlueFishCrisis's Avatar
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    Quote Originally Posted by 01stroker250 View Post
    I didn't check the reed because when reeds are not closing correctly usually you will get very poor idle or no idle at all and that is not my case. I have not check the piston wash yet, but I know the compression is good in all three holes. As stated in the last post I cut back the plug wire (Assuming that's what you mean by "plug chop"?) I have verified routing and connections on all fuel lines and there is really good fuel flow though the system and when I have checked the fuel bowl is always full. The restrictor is installed in the fuel return line as specified. I have not tested the stator, but could that really cause this kind of issues? What confuses me is it starts and idles perfect and sounds great.
    1. I disagree with your assumption on the Reeds. I would check them. When you are idling, the butterflies in the carbs are mostly closed which keeps the fuel air mix down in the bottom end. When you open up the throttle, the turbulence from the crankshaft and bad reed petals will allow fuel/air to escape back into the intake tract robbing you of power. Besides, if you are at a loss, why not check everything that you haven't yet checked just to rule it out.....
    2. Piston wash is not related to compression. It is the gauge of a proper fuel air mixture.
    3. A plug chop is bringing your ski up to full throttle while running and pulling the lanyard with the throttle held wide open. While still on the water, pull your spark plugs and take a look. Dark black and sooty is rich, chocolate brown is good, white/light grey is lean.
    4. Have you updated your tank venting or checked its operation? Without proper venting, the tank can develop a negative pressure and slow or even stop the flow of fuel.
    5. What kind of fuel filters do you have installed?
    6. What are your current carb settings? Low speed jets should be 1/2 out. Highs 1 1/4M 3/8C 7/8P
    7. Did you check your pop off pressure when you rebuilt the carbs? Did you replace the needle and seat as well?

  9. #9
    Thanks for the reply. So let me be this right as far as high settings... All three carbs have a slightly different setting?

  10. #10
    BlueFishCrisis's Avatar
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    Quote Originally Posted by 01stroker250 View Post
    Thanks for the reply. So let me be this right as far as high settings... All three carbs have a slightly different setting?
    Yes.

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