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  1. #1

    help with msx 140

    working on a 03 msx 140. it will only go 7mph in the water. acts like it boggs out. take it out of the water and it revs up great and idles but at 3200rpm. hooked up polaris digital wrench and got no codes. i tried a couple other things. thought maybe the tps was giving me trouble because i thought it was idling high. unplugged the tps to see if the unit would go into safe mode. rpms didnt drop. checked fuel pressure which was at 28psi. compression was ok, that was one of the first things i checked. next i sprayed a can of carb cleaner around the motor to check for air leaks. everything was sealed except for the base gasket area between the front and middle cylinder BUT the rpms didnt go up..the went down and if i kept spraying the motor would act like it would flud then kill the motor. anyone experience something simular?

  2. #2
    Click avatar for tech links/info K447's Avatar
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    Jul 2007
    near Toronto, Canada
    The high idle is a problem, for sure. The EMM normally controls the idle RPM to 1150RPM, in or out of the water.

    Is the RPM actually that high, or is the NGI display just wrong?

    You unplugged the TPS and the excess idle RPM did not change?

    Check the CPS sensor ohms, and check the encoder ribs on the flywheel. I expect they will be fine.

    Also check the TPS voltage and TPS percentage the EMM thinks it is seeing. Is it normal, or high?

    Does the Digital Wrench also show the high RPM?

    Try a spare EMM, sounds like yours might be going crazy...

    Is the carb cleaner you used for checking intake leaks actually combustible?
    It sounds like it was dampening the combustion, not increasing it.

    These Ficht fuel injected engines are not affected by air leaks at idle. That is why the throttle plates can have big holes through them! The fuel injected engines burn very lean at low RPM, with way more air flow into the engine than a carb'ed motor. The fuel injectors and EMM control fuel delivery based primarily on the TPS signal, not the intake air flow, air leaks or vacuum.

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