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  1. #1

    Question Polaris MSX 140 Missing at top speed

    Recently purchased a used 2003/4 MSX 140 - two stroke. It feels like it is missing at top rpm and seems slower then when I first took it out. Speedometer indicates only about 53 MPH. Good power until top speed, but engine seems to idle very rough.

    Looking for some help and suggestions as to what might be wrong. Only change from first time out is filled gas tank, which took about 10 gallons and changed spark plugs. Ski only has 25 hours on it. Do they all shake at idle?


  2. #2
    Click avatar for tech links/info, donation request K447's Avatar
    Join Date
    Jul 2007
    near Toronto, Canada

    What are the last four digits of the HIN number plate on the rear deck?

    Check the basics;
    Cylinder compression,
    fuel pressure (should be over 20PSI),
    correct spark plugs.

    Also check the ignition coil and spark plug wire ohms, make sure all connections are tight and clean.

    Remove, clean, and reconnect all the engine block grounds. There is one at the ignition coils, and another for the wire harness and battery negative at the engine block. You want clean and tight metal-to-metal connections.

    These 1200 engines do have some vibration at idle and around 2200RPM, but it shouldn't be shaking the hull apart...

  3. #3

    Thanks - Will Do

    The last four of the vin are D303.

    The plugs were replaced with PZFR6H - "NGK 7696" and I checked them on Friday. Seem to be burning ok without any significant fouling.

    I will follow your response instructions next week when we are back in Havasu. The idle appears rougher then your video displays, but that is the same vibration I was referring to.

    Really appreciate the time and info!

    Does anyone know a dealer that can check to see if all the recall/repairs were done to the ski with the full vin?

  4. #4
    Click avatar for tech links/info, donation request K447's Avatar
    Join Date
    Jul 2007
    near Toronto, Canada
    Your MSX 140 is a 2003 model, made in April 2003.

    If you cannot find a local Polaris dealer to check the HIN service history, call Jay at Sharp's Marine Repair. Jay is very knowledgeable regarding the Polaris Ficht fuel injected engines.

    Pay attention to engine RPM, not displayed speed.

    The NGI display can show you the RPM in digital format, not just the animated RPM arc across the top. The handlebar Mode button will switch the display modes.

    What RPM does it idle at?
    Should be rock steady at 1150RPM, in and out of the water.

    What is the maximum RPM the engine reaches, in the water?

    Do you see a red warning lamp, or any messages on the display, while the engine is running?

    Just to be sure you don't have something stuck inside the jet pump, visually inspect the jet pump impeller and stator blades. Look in from both the intake grate, and through the exit nozzles. Engine not running, of course.

    Read through the links below;

    Polaris Ficht Fuel Injected Engines

    Polaris PWC with fuel injected engines

    It is possible the problem (or part of the problem) is a failing TPS (Throttle Position Sensor). They only way to really tell is to swap in a known good TPS.

    I often recommend buying a new TPS. If it fixes the problem, good. If not, you now have a spare TPS, which can be a good thing later on. Cost is about $100.

    Ficht TPS versions, sources

  5. #5

    Taking it into Polaris Dealer

    Jay was great. Ran ski for me. No updates performed on ski and Jay assisted in locating a nearby dealer to perform them. If he was closer, I would take it to his shop in a heartbeat. Very helpful. Thanks. Will keep you posted on the results.

  6. #6
    Click avatar for tech links/info, donation request K447's Avatar
    Join Date
    Jul 2007
    near Toronto, Canada
    Quote Originally Posted by edb007 View Post
    ...locating a nearby dealer...Will keep you posted on the results.
    Who are you taking it to?

    Do let us know what the shop finds, fixes, and does

  7. #7

    Taking MSX 140 into Arizona West All Sport (Havasu)

    With Jay's assistance and recommendation, I am taking it into Arizona West All Sport in Lake Havasu City, AZ. It appears none of the eight service bulletins were performed on the ski and everyone agrees that once performed, all the problems should be resolved. AG(?) at Arizona All Sport was also very helpful.

    It goes in Friday and is suppose to be available by the following Friday, parts permitting.

    Will advise on results.

  8. #8
    Did you ever figure out this problem with you MSX? Mine is doing the same thing. Misses at top speed (occasionally), and I only get about 52 MPH out of it.

  9. #9


    My bad; forgot to post update as it solved all the problems. Arizona West All Sport in Lake Havasu City performed all the service updates under warranty and a few incidentals and it runs great. Most of the repairs were covered under warranty.

    I believe it was a combo of things that caused the slow speed and vibrations, including engine alignment and the throttle position sensor. It was not a problem with the warning system, which will cause the ski to slow way down.

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