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  1. #1
    Wrench's Avatar
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    '97 GTX 787 no spark

    Hi,

    I am working on a 1997 GTX with the 787. It was brought to me needing a starter bendix. The owner had take the exhaust off, mag cover, and flywheel off. I put it all back together, visually inspected the stator and pick up. All looked good, no bare wires or signs of damage.

    I went through carbs and put it all back together. Went to start it and it would not start. I pull the plugs and of course no spark. The rear electrical box has the black wire connect to battery ground. The fuse is good, and the two fuses in the front electrical box are good. When you put the key on there is no beeps. But it will crank when you push the button.

    The owner said the he got it from a guy that claimed it was running fine then just died and wouldn't start back up. To me that points towards the pick up, but I saw no visual damage, usually they are broken. So now I am thinking the MPEM could be bad but I hate to throw a $400 part at it and not have that be this issue.

    Does anybody have any good direction for me? I am a mechanical guy, not very good with electronics.

    Thanks


  2. #2
    Hurricane1000's Avatar
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    Try replacing the CDI located in the electrical box.

  3. #3
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    The CDI and MPEM are essentially one unit correct? Looking on ebay, $450-500 for one.

  4. #4
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    Quote Originally Posted by Hurricane1000 View Post
    Try replacing the CDI located in the electrical box.
    Well I went for it and bought a cdi. It has spark now! Thanks. But it won’t run. It hasn’t ran in years from what I’ve been told. Compression is good 148/150. Carbs were just gone through and cleaned. Spark plugs are just getting soaked with fuel. It will fire and run for 5-10 seconds then die. After cranking on it for 15 minutes (taking a few minute breaks to pull the plugs and dry them off) I notice that the negative battery post was melted. Negative cable is hot. I could see the positive doing that if you crank on it non stop, but the ground!? I followed it to the front of the motor to make sure it’s bolt to the front cover. The cable and bolt was warm.

    Any ideas for this new issue?

  5. #5

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    There is a lot of resistance at the cable end. May be corroded under insulation or bolt was not tight enough on battery.
    Last edited by Seadoo timebomb; 07-21-2020 at 10:42 PM.

  6. #6
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    Quote Originally Posted by Seadoo timebomb View Post
    There is a lot of resistance at the cable end. May be corroded under insulation or bolt was not tight enough on battery.
    Thank you sir

  7. #7
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    So itíll start and run, but only with the gas turned off. As soon as I turn the gas to ON or RES it starts idling down. I can keep it running with the throttle but itís really boggy and no adjustment to the idle screw will keep it running. Lows are at 1 turn out. Highs are all the way in. While keeping it running, if I turn the gas back off it will get responsive and it will rev quickly and sound cleared out.

    Again, I went through the carbs first thing. Fuel filters werenít plugged, check valves in good shape and all diaphragms looked good. I cleaned all the jets and needle/seats.

    I have no idea what else to check.

  8. #8
    Check and make sure the rotary valve is spinning

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