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  1. #1

    98 Seadoo Speedster - help

    ok, i have a 98 Seadoo Speedster w/twin 787's. Both motors run just fine, the problem is they wont run at the same time. When i start the port side and then start the starboard side it will kill the port side. if i start the starboard side first, the port will start and die. but they both run fine independently. i have checked all the fuses, i have unhooked the rectifiers. i have run additional grounds everywhere i can think of. i have switched out the DESS post, changed starter buttons. checked and cleaned all the grounds and connectors. i am at a loss.


  2. #2
    Any ideas???

  3. #3

    Join Date
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    Quote Originally Posted by oljoe View Post
    Any ideas???
    In what way does it die?
    Like shut off switch die? or cough/choke die out of gas?

    Just wondering if fuel pump is feeding both sides fuel?

    Sorry..Not a mechanic..just my question about what could be causing problem..

  4. #4
    It dies like you just shut it off. Both motors will run fine by themselves, just not together.

  5. #5
    This is how I run a jetski shop in the desert nmpeter's Avatar
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    sounds to me that the MPEM has a problem. That sucks as they are discontinued and used ones go for slightly less then the typical pound of flesh.

    however, I believe somebody sells a kit to allow you to use two standard 787 mpems in place. This trick however bypasses the throttle safety switches, which prevent engine starts when the pump setting isn't in "neutral"

    at the least-est open the mpem cover ( watch the screws) and take a peek inside for anything questionable . I'd reseat the fuses ( disconnect battery first)

    what's the history here..new acquisition?..old faithful ( till now)? any signs of shade tree chancery in the wiring?

  6. #6
    Just bought it, guy said he had a new starter put on the starboard engine and now this is what it does. I have been rebuilding Polaris and Sea-Doo jet skis for about 10 years so I thought I would take on another project, it this thing has me stumped. Any idea on where to find what two mpemís you can use in its place?

  7. #7
    All the wiring looks unmolested throughout the whole boat.

  8. #8
    I did t know the cover would come off this particular MPEM. It has a 204470155 MPEM in it.

  9. #9
    This is how I run a jetski shop in the desert nmpeter's Avatar
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  11. #10
    Thanks for the Info

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