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  1. #1
    SJ-(KY)'s Avatar
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    Installed MPEM an now its blowing fuses????

    Had a ski go down on friend of mine... We traced the electrical system down to the MPEM... Installed it today an now its just blowing fuses everytime I go to hook the battery up with the new MPEM... Has any of you ever have any type of similar problem when putting your new MPEM back on or have any type of idea whats goin on with this thing other than it sounds like a power is grounding somewhere....


  2. #2
    This is how I run a jetski shop in the desert nmpeter's Avatar
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    having more details

    would be really really helpful to solve an obvious short.

    please detail the source and part numbers of the original and replacement mpems.

  3. #3
    DISCONNECT the vts, just to rule out the relays sticking. That blows the 7.5 & 5 amp.

    ALSO POST YEAR & MODEL

  4. #4
    SJ-(KY)'s Avatar
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    Its a 1998 Sea-doo GSX Limited with a 951..... I matched the part #'s up last night an they were the same an both units are made by Denso is all I remember(Im at work now so I cant throw a part # out for a few hrs).. Im thinking possibly this why the orginal MPEM might have went out.. But i'll post up both part #'s from both MPEM's in a few hrs..

  5. #5
    SJ-(KY)'s Avatar
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    An btw the fuses its killing is the 15amp fuse on the module up front an the 15amp fuse for the battery in the back... Dident know if that would help..

  6. #6
    SJ-(KY)'s Avatar
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    Ok I have both MPEM's here in front of me an theres 3 different sets of #'s on this thing... The first # is on a yellow sticker that reads: 98M1330-A.... The second # underneith the first one is stamped on the plastic cover which reads: >PBT-GF40<........ The third # underneith that is the Denso sticker that reads: 071000-1330... Both ECU's Match each other on ever #... Any help at all would be gladly appreciated...

  7. #7
    This is how I run a jetski shop in the desert nmpeter's Avatar
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    and the replacement mpem came from

    where?..some unscrupulous types sell know bad MPEMs and then try to blame your "bad wiring" for "blowing the good one I sold you.

    I'd be checking the component side of the blown fuses for dead shorts to grounds..and the VTS advice was also quite good..typical blower of fuses.

    I assume you are connecting the battery correctly (sorry, I had to ask, s spent a few days helping somebody here recently with a fuel issue and it turns out the fuel tap was never turned on!)

  8. #8
    Richieb's Avatar
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    Save the cash, repair MPEM.

    This has been pulled on me a year or so ago.

    I ended with a fix for the problem after wrangling with the seller, which to be honest is a 50/50 argument, so no leg to stand on in reality.

    The 15amp fuse is the one on the charging circuit. It transpired that the rectifier in the MPEM had one of the rectifiers out, which was allowing full current back through the stator coils, and blasting the 15amp fuse out.

    I traced which of the 3 wires was connected to the bad side of the rectifier, spliced a rectifier into the line, and presto, problem solved.

    ONLY, it has cost me a $370 useless MPEM I had been sold.

    Still, it worked, and the cost was the same over-all.

    The MPEM has 3 wires (yellow) going to the MPEM, and by return to the charge feed wire to the battery. Of course, the other side is ground.

    A way to check to see if this is the problem, you can take these wires out of the connector(keep insulated tho). Fire the ski, and if the fuse stays in tact, it is the problem. Now, get a DVM, and see wich one of these yellows is 12v live. The one/s that are, you get a 15amp rectifier, and solder & shrink it into the loom somewhere safe. Reconnect the wires into the connector, and the problem will vanish for you.

    Just to re-cap......

    The current from the battery can flow back to the stator charge coils, and will blow the 15a fuse unless reverse flow current is blocked to all of the 3 charge wires. A rectifier is the "one way valve" to control this.

    The rectifiers are connected to a common point which feeds the positive to the battery thro a 15amp fuse, and the three "other-ends" are connected to one/individual yellow feed wires from the magneto. All we are doing here is replacing the internal shorted rectifier to one further along the wire, which electrically is identical.

    Now this is a fix which all 2-smoke seadoos may benefit from at some time, and save the expense of a replacement MPEM.

    I have considered making a patch lead to sell as a fix'n'plug adapter. I suppose a pictorial repair kit would be another idea.

  9. #9
    SJ-(KY)'s Avatar
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    Thanks a bunch Richie I'll be trying that tomarrow.... Where might I find one of these rectifiers? I wanted to get a good look at the Starter an main wire going to the starter an ground so I pulled off the Pipe so I could take a look an what a pain in the ass!!!! Geeeeeeeeeeze!!!

  10. #10
    Richieb's Avatar
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    Ok, just get the connector at the mag end, take out one connector wire at a time if you want, they will be yellow.
    Put fuse in, meter the wire when connector back in, and see which one is trying to discharge the battery thro the stator coils(This is why it blows the fuse)

    Bear in mind there could be more than one phase of the rectifer with a short on it.

    When you find it, grab a rectifier of 5amp or more value(Radio shack do them), put it in the end of the connector, DVM it to see which way round it goes, as one way it will conduct, and the other it won't. Remember what the marking or direction it faced, and then solder it in somewhere in the loom. Seal it with Heaty-shrinky-thingy, and done.

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