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  1. #1

    SL 750 fouling plugs


    I just picked up a 95 sl750 for $250 with title! it didn't come with a trailer though. The owners said the the sparkplugs would foul after a day of running it on the water. They took it to a shop where the compression was checked. They were told the compression was low and that was causing the fouled plugs and it needed the top end rebuilt. Said it was around 110, and should be 140.. I would have thought it would run fine at 110 aslong as they were all close in that range. When I got it home I checked the compression and found it to be 130,125,130! It starts right up and sounds good I think. (my first jet ski)

    My question what else could be causing fauled plugs? oil system over oiling? They put brand new plugs in it, and they are covered with oil just after a few 30 second starts. I don't doubt it was fouling the plugs, but I don't think this is a compression issue... I would like to check a few things before I take it out in the water and end up with some fouled plugs!!


  2. #2
    ripcuda's Avatar
    Join Date
    May 2010
    Newman Lake, WA
    Welcome to Green Hulk!
    Sounds like you got a sweet deal on a 2 seater. Okay, so before you get all itchy and go put the ski in the water and try it out, PLEASE do some maintenance and preventive measures first! You would be surprised how many folks pop in hear to ask about their new-to-them ski that they just messed up on the first trip out.

    These jet skis are pushing 20 years old and they have a few Achilles Heels that need to be addressed to keep them running well for years to come. The best thing is to start here:

    Tons of very important information about getting your ski in tip top shape. And I'd bet you end up fixing your problem when going through and doing the recommended stuff like rebuilding your carbs and putting in a new triple outlet fuel pump.

    That said, your problem could be a carb issue. I'm not sure on your '95, but my '94 750 injects the oil into the intake manifold below the carb, while my '96 780 injects into the top of the carb. And my '94 has a non-variable oil pump while the '96 has a throttle-linked variable oil pump. If you have a variable oil pump... one with a small rod that connects the arm on the oil pump up to the carb throttle linkage... then it's possible this rod came off or is now stuck in full rich oil mode. While your at it, check the oil injection lines from the oil pump (right side lower block below intake) and make sure the lines are good, not-cracked, on tight, not-leaking.

    That should get you started... especially the link to the online knowledge bank.

    Good luck!

  3. #3

    Join Date
    Jun 2012
    Swartz Creek Michigan
    I would check the oil pump rod linkage clip. If it is broken it will over richen the mix.

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