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  1. #1

    MX 140-- Only idles

    I have a MX 140 which has ran great for me--Until yesterday. Now it will only idle and putter around. I am planning to replace the spark plugs (but do not think this will fix my issue). Machine acts like it is not getting fuel. Throttle seems to and appears to be attached OK. Looking for suggestions. This is the 3rd season I have owned the machine. This was the maiden voyage for the season......Ran fine on Saturday, but developed this issue yesterday. Does this model have a fuel filter?? Thanks


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

    My guess is that the TPS has failed. The TPS provides the signal to the engine computer that you are squeezing the throttle.

    TPS is located at the rear end of the throttle bodies, tucked under the base for the flame arrestor.

    Install only NGK PZFR6H spark plugs, no substitutes.

    Fuel filter is part of the fuel pump, inside the fuel tank. Not normally replaced unless the fuel has been contaminated.

    Remove the flame arrestor cover with engine off. Look down the throttle bodies while you squeeze the throttle. If the three butterfly valves open, then the throttle cable is still connected.

    See my signature links for some common maintenance items and known issues. Do not overlook servicing the through-hull bearing carrier.

  3. #3
    I had already installed AC delco plugs ...prior to seeing your post. Why only NGK plugs? I test ran it...out of water and it revved up..normally. Thanks

  4. #4
    ThrottleOut's Avatar
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    The NGK PZFR6H are designed specifically for the Ficht injected jet ski and boat motors. While a plug that cross references to it will physically fit it will not run correctly. Hard to describe but if you compare the NGK to a cross-referenced plug you'll see a big difference. The NGK puts the electrode pretty much right in the fuel spray from the injector. I need to snap a few pics of the two side by side next time I get a chance.

  5. #5
    Yeah I compared....look different. Plan to get the NPK tomorrow.

    You have a great site for Polaris owners. I've been trying to locate a diagram/instructions on how to service/grease the in hull bearing. But have been unable to do so....probably overlooking it....do you have a link. Thanks for your help.

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    Click avatar for tech links/info, donation request K447's Avatar
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    Quote Originally Posted by toddrnlds View Post
    Yeah I compared....look different. Plan to get the NPK tomorrow.

    You have a great site for Polaris owners. I've been trying to locate a diagram/instructions on how to service/grease the in hull bearing. But have been unable to do so....probably overlooking it....do you have a link. Thanks for your help.
    MSX hull uses a different through-hull bearing carrier than all the other models.

    The MSX assembly is periodically rebuilt, not lubed. There is no grease fitting. Rebuild it every 100 hours or every few years, roughly. More often in salt water.

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    Click avatar for tech links/info, donation request K447's Avatar
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    Quote Originally Posted by toddrnlds View Post
    I had already installed AC delco plugs ...prior to seeing your post. Why only NGK plugs? I test ran it...out of water and it revved up..normally. Thanks
    The ignition system on the Ficht engines fires the plugs using a multiple strike per power stroke cadence. The NGK PZFR6H plug is designed to properly resonate with this ignition system and properly deliver the required spark intensity.

    People who report using non-NGK spark plugs on the Ficht fuel injected engines report weird engine problems including poor running, low power, bad idle, etc.

    An engine with problems will often still appear to rev happily enough out of the water. In the water is a different story.

  8. #8
    Update... After replacing the plugs. We tested at sand pit.... Ran well, but the pit is not big enough to really open it up. So we headed to the lake. Jet ski ran well for approximately 30 minutes. Then back to the same problem..... Jetski will only idle. No response from the throttle. Do you suggest replacing the TPS? Why do you think it runs good for 30 min the back to idling?.

  9. #9
    Click avatar for tech links/info, donation request K447's Avatar
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    Quote Originally Posted by toddrnlds View Post
    Update... After replacing the plugs. We tested at sand pit.... Ran well, but the pit is not big enough to really open it up. So we headed to the lake. Jet ski ran well for approximately 30 minutes. Then back to the same problem..... Jetski will only idle. No response from the throttle. Do you suggest replacing the TPS? Why do you think it runs good for 30 min the back to idling?.
    Which spark plugs are now installed?

    It ran well? How well? What was the maximum sustained RPM on the water at full throttle?

    Was throttle response smooth, linear and 'normal'? Any surging or unexpected change in engine power while riding around?

    I would still suspect the TPS (or the wiring to the TPS). And even if it turns out the TPS is not the problem, it is always good to have a spare TPS on hand. When the TPS does go bad, there is simply no work around.

    Make sure the water cooling through the EMM is actually flowing. The EMM will internally overheat and do strange things if it is not properly cooled. You may not see any warnings on the display even if the EMM is cooking itself.

    Check the small water hoses for kinks. Check the elbow fittings on the stator cover for blockages.

    On my own MSX 140 I capped off the small hose fitting at the exhaust outlet and routed the EMM water exit to an external 'pisser' fitting on the side of the hull, so I can visually confirm water flow through the EMM.

  10. #10
    Kids were the ones riding the ski....so not sure what the top speed was. But it appeared to run well.
    NPK plugs are now installed.

    Where do I order a new TPS??

    I will check the hoses. Do you have a picture of which one to check?

    Thanks for the help.

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