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  1. #1

    96 SLT 780 MFD not working

    So basically what happened was, I hooked up a battery pack to get this ski running as I had a battery that wouldn't charge, still waiting for a new one...

    Well I started the ski and a couple minutes into it running the positive clamp fell off and the mfd went out. Ski was still running fine with this off. I shut it down. Reconnected and fired it back up. Display won't turn on now.

    The only thing I knew to check was the push button breaker on the electrical box and that was fine because I'm thinking it wouldn't start if that was popped.

    Any help Thanks guys


  2. #2
    Click avatar for tech links/info, donation request K447's Avatar
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    Welcome to the Hulk

    As you have learned, it is dangerous to run these machines without a proper battery installation.

    The PWC electronics do not like being jump started, and are not happy if the battery becomes disconnected while the engine is running.

    Don't run it without installing a proper battery.

    Click here for the Polaris Service Manuals.

    Open the electrical box, and check the 1/4 Amp fuse for the MFD. Only replace it with another 1/4 Amp fuse, not a higher rated fuse. Radio Shack is one source.

    If there is another fuse in there, it will be for the bilge pump (if you have a bilge pump).

    Do not run the engine without cooling water for more than 15 seconds or so.

    When connected to a garden hose for cooling, do not run it for more than two minutes on the hose, or the seals in the jet pump can over heat.

    When using the hose for cooling, always follow this sequence;
    Engine start
    Water on
    Water OFF
    Engine off

  3. #3
    Thanks for the quick response and amazing answer, I'll check it out and let you know the outcome, thanks again

  4. #4
    It worked thanks. For the fuse I put in the same one 250v 1/4 amp. The only difference was the original AGC and the new one is AGE. Not sure what that means, or if it matters.

  5. #5
    Lake Mead Bum & BTLS Mark starflight's Avatar
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    Never heard of an age. It's not a time delay fuse is it? If it is, thats not what you want.

  6. #6
    Click avatar for tech links/info, donation request K447's Avatar
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    Quote Originally Posted by rc3477 View Post
    ...For the fuse I put in the same one 250v 1/4 amp. The only difference was the original AGC and the new one is AGE.

    Not sure what that means, or if it matters.
    Doesn't really matter, as long as the Amp rating is 1/4 Amp, it should be fine.

    Slow-blow 1/4 Amp fuses will also work, but they tend to be fragile, and would likely fail when used in a physically rough environment like a PWC.

    BTW, I have not heard of an AGE type fuse - you sure about that code?

  7. #7
    Lake Mead Bum & BTLS Mark starflight's Avatar
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    Quote Originally Posted by K447 View Post
    Doesn't really matter, as long as the Amp rating is 1/4 Amp, it should be fine.

    Slow-blow 1/4 Amp fuses will also work, but they tend to be fragile, and would likely fail when used in a physically rough environment like a PWC.
    The time delay fuses I deal with allow a way larger amount of current than the rating of the fuse as long as its for a short amount of time. i.e. an
    frn-30 is a 30 amp fuse but will allow more than 70 amps for a short period of time without blowing the fuse. Are ya sure a time delay fuse would be ok?

  8. #8
    Click avatar for tech links/info, donation request K447's Avatar
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    Quote Originally Posted by starflight View Post
    The time delay fuses I deal with allow a way larger amount of current than the rating of the fuse as long as its for a short amount of time. i.e. an
    frn-30 is a 30 amp fuse but will allow more than 70 amps for a short period of time without blowing the fuse. Are ya sure a time delay fuse would be ok?
    At the low current levels of the MFD circuit, I think it would be OK.

    In the Polaris wiring, normally there are only two ways I can think of for the MFD circuit current draw to be excessive.

    Reverse battery polarity, which will the drive current up very quickly, and in this case the slow-blow fuse might allow more than the MFD can safely handle. But we know that MFD can be damaged even with a fast fuse, if the polarity is reversed.

    A wiring short, which should blow any 1/4 Amp fuse, slow or fast type.

    In the 1/4 Amp glass fuse sizes, the Littlefuse Slo-Blo has these specs for overload conditions;

    Load % - Time delay
    100% - 4 hours, Minimum
    135% - 1 hour, Maximum
    200% - 5 sec. Min, 30 sec. Max

    That means a 1/2 Amp fault current (200% load) will blow the 1/4 Amp fuse in under 30 seconds, maybe as fast as 5 seconds. Higher currents should be even quicker.

  9. #9
    It said age 1/4 amp 250v also said something about fast blow or something. A little off topic do you guys happen to know what the idle rpm is out of water

  10. #10
    Click avatar for tech links/info, donation request K447's Avatar
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    Quote Originally Posted by rc3477 View Post
    It said age 1/4 amp 250v also said something about fast blow or something.

    A little off topic do you guys happen to know what the idle rpm is out of water
    AGE fuse type sounds fine.

    Out of the water, the engine will idle quite fast, usually about double the in-water idle RPM, give or take.

    You cannot accurately set the idle out of the water, as some engines will drop more RPM in the water than others.

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