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  1. #1

    Misfire problems with Aquatrax F12x

    Hi All,

    I am having some problems with my newly acquired F12x from circa 2002. Basically it is misfiring on cylinders 2 and 3. It will start and run on the trailer but will not run correctly in the water at all as you can imagine. I can unplug cylinder 2 and 3 coil packs and it makes no difference to the running of the engine, at all.

    When this first happened i swapped around coil packs and plugs and no difference, I then swapped around fuel injectors and again no difference. I went testing the WGS and also the Actuator and miraculously when i put the ski back together it ran perfectly - on the trailer and then by the time i got to the water it was back to itself again.

    I must emphasise that i am getting no codes. I had bought a Macsboost module and did get an FI light with that once but when it was unplugged it was fine and i have left it unplugged since. (I dont think the Macsboost controller is the issue im just trying to eliminate everything). The only light i do get is the battery symbol occasionally if it has turned over for a while or if it has been started 2-3 times in quick succession, when the light comes on the engine is turned over quickly and it does not sound like its low on current.

    Today i changed out all of the plugs for new IMR 9D9H's and still the exact same. I swapped the MAP sensor and WGS for items which were known good on my friends ski.

    I am really losing my patience with it at this stage and im frustrated as i am based in Ireland and there is no where to get parts or advice. It seems new parts are only available in the States.

    My thoughts now are that it is a wiring harness issue but i dont want to just buy more parts to find out its not the problem. I am a BMW Tech so while jet skis are not my thing i have a fair idea of what im doing mechanically.

    Any idea what could be causing it to properly cut power to 2 cylinders and not put on a code??


  2. #2
    Jake Speed's Avatar
    Join Date
    Jan 2007
    New Jersey
    Did you test for spark?

  3. #3

    Join Date
    May 2011
    Do a compression test first, all 4 cyls should be within 5psi of each other

  4. #4
    Do have a spark in all cylinders, it appears to be cutting the power to the injectors at cylinders 2 and 3.

    Have compression tested it and it's healthy and even across all 4.

  5. #5
    jlfx car audio's Avatar
    Join Date
    Jul 2011
    jackson, TN
    Get a test bulb to check injector pulse

  6. #6
    supermac's Avatar
    Join Date
    Dec 2005
    Mooresville, NC
    Can you swap the ecu and/or harness with your friend?

  7. #7
    Ski is now with a honda main agent I found. Unfortunately he is stumped as to what might be the trouble.

    My friends ski is an r12x and ecu is in a different place so didn't want to do too much dismantling to it as he uses it regularly. If we don't get something sorted this week I'll have to do that.

  8. #8
    CelticCrew's Avatar
    Join Date
    Jul 2009
    Frederick, MD
    Centralcyclepowersports usually has the best prices on the ecm/ecu.

  9. #9
    Did enyone found the solution for the problem mentioned above? I've got the exact same problem.

    Started out as an intermittend problem, but turned into a constant problem since then. What have I allready tested:

    Compression: Fine
    Spark: yes at all cilinders
    Injectors, were tested and appeared fine but had them cleaned anyway
    electrical, tested all possible sensors for restistance values, all seem correct.

    Yesterday I've been at the waterside again, and it wouldn't rev' up above 3000rpm. The only thing I could determine was that pulling the connector from coilpack 1 or 4 caused the engine to cut out. Unplugging 2 or 3 was not causing any difference at all. Also, the sparkplugs from 2 and 3 were much darker, actually black. Both sparkplugs 1 and 4 looked fine.

    I've checked the sparksignal toward the coilpacks with a scope, all looked exactly similar. I've done the same thing to the injector wiring. All fine..

    I'm pretty fed up with this problem, even had it at a specialist here in Holland ( ski's are rare, let alone a specialist), but after a few days he also gave up.

    The only thing I can image that could cause such a problem is the fuel pressure regulator, but I've checked the manifoldside for fuel and even mounted a small transperant hose between the regulator and the manifold. But not even a dash of fuel could be seen..

    In my opinion a fuel leakage through the regulator toward cilinder 2/3 should be clearly vissible if it is causing such rough running and black sparkplugs. is there a neat way to check this pressureregulator?

    furthermore, a leaking head gasket between cilinder 2 and 3 should have come up testing the compression ratio, so I've kind of ruled that out also.

    Help is very much appreciated!

    Kind regards from Holland!

  10. #10
    xdrian's Avatar
    Join Date
    Nov 2008
    Brisbane Australia
    sound like me story as well

    compression was fine all 180psi my number 1 and two yes head gasket small water leak doesn't take much.

    You could try a leak down test look up on net how to do.

    I tryed but couldn't find a plug to fit spark pulg.

    Also when you take the cams off check under the cam buckets the cottors are in place I say with good compression that they will be in place but check first.

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