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  1. #1
    Haven't fallen yet. MJE's Avatar
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    1390 has power on trailer, wont rev in water. suspect efi controllers

    Whatever you guys guess is about as good as a guess of mine. I suspect its the efi controllers which are garbage. One failed already (lights stopped working etc)...then the second one "failed" and the other ski went into limp mode (they sat for 4 years, moisture perhaps, who knows) I tried swapping the "questionable" efi controller with my 1390 ski and it has the same symptoms...lights go on, i can adjust this controller...however it will not go over 4k rpms. On a trailer it seems to run strong, revs up etc. On the water it ONLY revs up when the ski comes out of the water and isnt under a load. Compression is 150,150,145 as lowell cut it years ago. Could it be a stuck reed petal?

    HELP before I sink this thing and move on.

    -Mike


  2. #2
    Haven't fallen yet. MJE's Avatar
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    Could it be a fuel pump issue? Didn't think of that.

  3. #3
    Prism's Avatar
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    Just for giggles, try changing sparkplugs and retest. When it won't go over 4k are all the jugs getting warm and the same temp?

  4. #4
    Quote Originally Posted by MJE View Post
    Whatever you guys guess is about as good as a guess of mine. I suspect its the efi controllers which are garbage. One failed already (lights stopped working etc)...then the second one "failed" and the other ski went into limp mode (they sat for 4 years, moisture perhaps, who knows) I tried swapping the "questionable" efi controller with my 1390 ski and it has the same symptoms...lights go on, i can adjust this controller...however it will not go over 4k rpms. On a trailer it seems to run strong, revs up etc. On the water it ONLY revs up when the ski comes out of the water and isnt under a load. Compression is 150,150,145 as lowell cut it years ago. Could it be a stuck reed petal?

    HELP before I sink this thing and move on.

    -Mike
    Check to see if the controller is properly grounded.
    Check to see if the exhaust stinger section clamps, and exhaust system is tight w/no leaks for proper scavaging.
    Check to see if CATCON has broken away from housing-assuming you don't have a D-plate of course.

    As already stated, obvious simple fixes like plugs, as well as bad gas could also have caused this... . 'Shocking' the ski with seafoam is another cheap/easy troubleshooting method for a slightly clogged/water in system/ski.

  5. #5
    Haven't fallen yet. MJE's Avatar
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    New controller, still same problem. I'm going to pull the exhaust tomorrow and triple check that everything is sealed up. If there was an exhaust leak (say at the dual clamps and water jacket layer)...would that cause the issue that lets the engine rev up on trailer, bog and stay under 4k on water? I do know when the ski comes out of the water it revs up like its running normally. It's old fuel, but almost empty. I'm going to run my yamaha diagnostic scan tool on it tomorrow and see what the random check engine light I got is.

  6. #6
    Quote Originally Posted by MJE View Post
    New controller, still same problem. I'm going to pull the exhaust tomorrow and triple check that everything is sealed up. If there was an exhaust leak (say at the dual clamps and water jacket layer)...would that cause the issue that lets the engine rev up on trailer, bog and stay under 4k on water? I do know when the ski comes out of the water it revs up like its running normally. It's old fuel, but almost empty. I'm going to run my yamaha diagnostic scan tool on it tomorrow and see what the random check engine light I got is.
    ..yes. Mine did that when I bought it new. The manuf/dealer apparently did not check to see of the clamps were tight... . Also, if the bog is more of an intermittent type/missing feeling at top-end rpm's only, then check to see if you've got a leaking head gasket, especially if you're running 150+ compression. Just another thought...

  7. #7
    Happily Self-Employed WFO's Avatar
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    if the fuel is old, I would start there

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