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  1. #1

    Need some advice with TPS issue, 2003 Polaris MSX140

    I have a 2003 Polaris MSX140 with 72 hours. Bought it from a co worker about 2 yeard ago and got it at 60hours and i had to redo the through hull seal, shaft, etc. I have used it without issur ever since for the last 2 years.

    I recently took it to Canada and ran it on fresh water lake for about a week about 2 months ago. The second to last day of the trip I noticed that every one in a while the ski would bog and then bounce off of half throttle on occasion when riding. Also Noticed the overheat light come on...but all the cylinders felt ok.

    Got the ski home and found the regulator had fallen off in the tank so I reinstalled it and safety wired it to the pump body. Also tested the pump and cleaned the sock. Reinstalled everything and ski would start and run for a few seconds but had trouble responding to throttle. A slight amount of throttle would bog it and stall it and if you held it wide open it would slowly struggle to raise rpm.

    I verified spark at all cyclinders, replaced the plugs, verified all injectors fire, removed and checked the computer water passage which was clear and verified all water lines are clear. Checked all connectors for corrosion and gound none as well as fresh dielectric grease and verified terminal quality and tightness.

    I unplugged the tps and it started and ran fine but with the tps unplugged it screams at 4500 to 5000 rpm. I bought a new sensor and installed it. I replaced the tps sensor and and it starts but stalls instantly. If I give it any throttle all it does is bog the engine.

    Unplugged the sensor and it screams at 4500 rpm but runs fine at that rpm with no misfires or anything. If I take the sensor off of the intake and spin it by hand I can run the engine just fine by matching the throttle cable to the position I turn the sensor to but as soon as I reinstall the sensor...it runs like crap again. Any ideas? Is there a tps adjustment?

    Why does it scream at 4500rpm when the tps sensor is unplugged?

    Thanks, mike.
    Last edited by K447; 06-12-2015 at 12:45 PM.


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

    Your set of symptoms is unusual.

    With the TPS unmounted from the throttle body you can control the engine right down to normal stable idle and also rev up to near redline, correct?

    This is out of the water I assume.

    I am leaning towards the EMM needing repair, but I cannot be certain.
    Last edited by K447; 10-13-2014 at 11:27 PM.

  3. #3

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    My two cents for this discussion
    check that The intake axis is really operate the TPS.
    If you can control the engine by manual TPS spin then all you need to check is that the throtle is moving the TPS.
    Start with removing the TPS and check if the throtle is spining the axis that operate the TPS

    Gabi

  4. #4
    GGG's Avatar
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    When you unplug the tps from the harness, the engine should idle and only idle. The fact that it is reving up seems like it could only be resistance in the wiring harness or the emm. With that said, i have never come across a symptom like that before but if i did, first thing i would do is try a donar emm

  5. #5
    Yes the intake axis turns the tps correctly. I dont know anyone with a donor emm to try nor do I have the money to buy one without knowing for sure that the emm is the fault. I just dont know where to go from here..

  6. #6
    Banned User
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    Where are you located?

  7. #7
    Quote Originally Posted by BryanP View Post
    Where are you located?
    Long Island, NY. Just checked fuel pressure..24-25 psi when i can get it running, so that seems good. Ive heard of the EMMs going bad just wierd because it was just working fine...

  8. #8
    Click avatar for tech links/info, donation request K447's Avatar
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    Quote Originally Posted by K447 View Post
    Welcome

    Your set of symptoms is unusual.

    With the TPS unmounted from the throttle body you can control the engine right down to normal stable idle and also rev up to near redline, correct?

    This is out of the water I assume.


    I am leaning towards the EMM needing repair, but I cannot be certain.
    You have tested the engine with the TPS in your hand, but this is only out of the water, correct?

    Have you checked the voltages on White/Red fuel injector wire? Do not unplug an injector, find another place to tap into White/Red. Black meter probe to engine ground. Voltage should be very close to 45 volts and stable as RPM varies. If the voltage is weak or sags when you squeeze the throttle then something is wrong.

    Also verify that the engine is actually firing on all cylinders. They should be equally warm after a short test run on the trailer (maybe 20 seconds without cooling water).

    Correct spark plugs installed?

    Check that the wires to the TPS wire harness connector are not damaged, frayed, loose pins or open circuit internally. There should be five volts between the outer two pins at the TPS connector. The center pin is the signal back to the EMM. Approx .4 volts at idle position.

  9. #9
    Quote Originally Posted by K447 View Post
    Quote Originally Posted by K447 View Post
    Welcome

    Your set of symptoms is unusual.

    With the TPS unmounted from the throttle body you can control the engine right down to normal stable idle and also rev up to near redline, correct?

    This is out of the water I assume.


    I am leaning towards the EMM needing repair, but I cannot be certain.
    You have tested the engine with the TPS in your hand, but this is only out of the water, correct?

    Have you checked the voltages on White/Red fuel injector wire? Do not unplug an injector, find another place to tap into White/Red. Black meter probe to engine ground. Voltage should be very close to 45 volts and stable as RPM varies. If the voltage is weak or sags when you squeeze the throttle then something is wrong.

    Also verify that the engine is actually firing on all cylinders. They should be equally warm after a short test run on the trailer (maybe 20 seconds without cooling water).

    Correct spark plugs installed?

    Check that the wires to the TPS wire harness connector are not damaged, frayed, loose pins or open circuit internally. There should be five volts between the outer two pins at the TPS connector. The center pin is the signal back to the EMM. Approx .4 volts at idle position.
    Yes this is on the trailer without water (afraid the engine will stall with water hooked up and thats a no-no)

    Injectors reading 44.75v at idle and does not change at any throttle position. I have a 5V reference on the two outer pins and read 5v while running. Checked the center pin around .4v at idle goes to 4.7v at full throttle and smooth gain as the throttle is depressed and released. And all these tests were done with the TPS hooked up and in its correct location. The spark plugs are all brand new PZFR6H and the wires were replaced not too long ago. I cannot find any frayed, loose connections, or damaged wires from the TPS connector to the EMM main harness. All 3 cylinders stay about the same degree after running for a bit on the trailer. Read temps with heat gun Front to Rear after 10seconds of running at mixed rpms the temps are 105 106 105.

  10. #10

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    have you tried another tps

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