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  1. #1

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    2003 MSX 140 dies when you open up on the throttle.

    I finally have my 5 year old project running.
    It idles at 1150 but as soon as you open her up she sputters and dies.
    I think it is one of three things.
    1) Bad TPS?
    2) Starvation of fuel possibly gas tank fuel pump?
    3) Fuel Injector voltage off?

    Any help would be greatly appreciated?
    The computer was repaired by Ficht EMM repair.

  2. #2
    martincom's Avatar
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    You're on the right track.

    1. The only method to test a TPS is a swap out with known good unit. Sometime defective units will not provide a check engine. Any check engine lights/messages?

    2. Check the fuel pressure when in failed state. Here is a link to a cheapy gauge:

    http://www.tooltopia.com/otc-tools-5..._intid=OTC5630

    3. Check the injector supply voltage on white/red wire. Do so by inserting a small probe into the rear of the connector housing to contact the terminal back side. You must measure with everything connected or you'll receive an erroneous reading.

  3. #3

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    Well I sent the ski to a shop last year and they got it running. This was a year ago. I put it in the water at the boat ramp and the through hull bearing assembly was leaking where it meets the ski body. I took the jet pump out and reinstalled with new bearings and 3m 5200 which worked great. I rebuilt the jet pump and using all the info here purchase the alignment tool and spacers for the pump to get the pump spot on. Had to replace the impeller as that was worn out. That was another $1300 to ebay.

    I checked the fuel pressure and it is at 25 psi while running.
    I checked the injector voltage it is at 48 volts running.
    I installed another TPS still same problem.
    It idles at 1150 to 1200 solid. It starts ever time.
    It dies above 1200 rpm but if given enough gas it will rev from 3000- 5700 on the trailer in the water.
    It always dies when revs drop down to below 3000 rpm.
    Any help would be appreciated. Harris repaired the Emm in the past.
    I am stumped.


  4. #4
    bradmiester's Avatar
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    Dear Andrew K,

    As I've had a few Polaris from my snow mobile days....and raced for Husky and KTM, and owned The Original JETSKI 650 from Kawi....

    When is the last time you did a top end on this 15 year old Ski? Bottom End? It sounds like your having Power producing problems under load.

    if the Reeds are good.... and the TPS is set correctly (not sure if thats variable or not), I'd pull the head and take a peek inside one or all of the cylinders.....

    I know it's backbreaking doing the "Yoga Position" and even on a maintenance stand with the correct scaffolding can be a pain in the ass.....but, I think thats probably your next point of attack to tackle your power and powerband running issues.

    Keep us posted and perform a Cylinder pressure and bleed check before you pursue the Top End.

    Cheers

  5. #5
    Click avatar for tech links/info K447's Avatar
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    Quote Originally Posted by andrewk View Post
    ... Harris repaired the Emm in the past.
    ...
    That may be your problem. If the repair was not done correctly, or something else failed after you got it back.

  6. #6
    martincom's Avatar
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    The MSX140 had a feature to accelerate the engine when the steering was hard over in either direction and watercraft speed was in a certain range. I believe it was called "Enhanced Steering". It interfaces with the EMM via the TPS connector. It mates with the TPS connector from the EMM and, in turn, the TPS connects to it. Let's try disconnecting it from both and connecting the TPS directly to the EMM, which would be bypassing this "Enhanced Steering".

    It sure seems like the EMM is not receiving a signal from the TPS.

    Once you have it bypassed, if the problem persists, perform DC voltage measurements at the EMM TPS connector. One pin will be ground, another +5 volts and the third's voltage should vary with the throttle position. Let us know what the latter is at idle, mid-throttle, and wide open. These voltage measurements will have to be made with the engine running or the DC power bypass plug connected to the harness connector that mates with the EMM power board DC output. K447 has details on constructing this simple bypass plug on his home page or in the sticky that discusses EMM diagnostic software communications cables.

  7. #7

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    The engine has been completely rebuilt. New pistons, new Nikasil plating, new gaskets. Today I tested the TPS. I have two of them.
    One was sold as new.
    I jumpered the 8 pin connector to power the emm. The first TPS showed 5 volts at the red wire. Idle was .284 volts. max was 4.29 volts.
    It appeared to progress smoothly in voltage increases.
    The second TPS the supposedly good one from EBay. Red wire showed 5 volts. Idle was .197 volts max was 4.92 volts again the voltage increases appeared smooth.
    Where is the connector for the enhanced steering located ?

  8. #8
    martincom's Avatar
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    It appears as if both your TPS units are functioning normally.

    The TPS plugs into the Enhanced Steering harness, just above the starter solenoid. The enhanced steering mates with the TPS plug from the main harness just above the starter solenoid, also. I've attached the simplified wiring diagram from the service manual.
    Attached Thumbnails Attached Thumbnails Polaris_2004_Service_Manual_(9919061)_02 286.pdf  

  9. #9

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    Today I took the ski down to the ramp and tried again. On the weekend I adjusted the throttle plates as they were not opening all the way.
    I started the ski and it idled at 1200. I let the motor warm up and then opened her up she reved to 6800 rpm and down to 3000 rpm with no problems. As soon as rpm's dropped below 3000 the motor died. It started up and idled at 1200 no problem every time.
    When the engine idles and I crank the steering the motor does not increase in rpm for the extra steering input.
    I unplugged the single connector from the esp controller to the ots switch which is supposed to close when cranking the steering to then close a circuit to boost rpms for steering and nothing happened.
    I still wonder why I have a mysterious dead spot. form idle to 3000 rpm.

  10. #10
    martincom's Avatar
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    Did you ever completely bypass the Enhanced Steering system by connecting the TPS directly to the EMM, rather than being routed through the Enhanced Steering Circuitry, as previously instructed?

    Enhanced steering throttle increase only incurs if the watercraft is moving within a certain speed range. Do you have the service manual which explains, in detail, how it operates?

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