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  1. #1

    96 Polaris 780 SLX engine running rough

    I am a newbie so be gentle. I have a 96 780 LSX which was running just fine except for one thing, the MFD would not light. I came across this site when looking for potential fixes. After reading about the fuse in the electrical box, I opened it up, replaced the fuse and lo and behold, the MFD came back to life. Unfortunately, once I got the unit all buttoned back up and took it for a test drive, the engine is running extremely rough. This was not the case before hand. I reopened the electrical box and checked the connections but that did not help. Once the RPMs get above maybe 2500, the engine just sort of shakes. Max RPMs maybe 3500 which gets to about half speed from before the MFD issue. I know nothing about engines so unless this is something simple, I will likely need to take it in. Just seems odd that all was fine before I replaced the fuse. Can anyone offer some suggestions?

  2. #2
    She likes the bike. But the ski gets her wet!!!! xlint89's Avatar
    Join Date
    Oct 2006
    Cleveland OH
    Welcome to the Hulk.

    Unplug the MFD from the back of the unit and see if that helps out. (just for testing purposes)

  3. #3

    96 Polaris 780 SLX engine running rough

    How do I do that? Do I need to remove the MFD?

  4. #4
    If you search the forum you will find this has been covered many times. Search for "Limp Mode"

  5. #5
    Thanks Orangeman.

    You are right, the issue is that I am in LIMP Mode for low fuel (one bar showing). I put in about 5 gallons of gas and the guage didn't move. Probably a float issue?

    Some more tidbits of info before I tackle that however. When I replaced the fuse for the MFD and it finally lit up after years of being asleep, I also pressed the buttons for a while trying to set the clock and went into CAL mode on the display then eventually got out of it. The ski was on a shore ramp at about a 15 degree incline at the time. Does CAL mode also calibrate the fuel gauge as well or have some correlation?

    I just put the unit in the water and went through the CAL sequence again. CAL 0000 appears for about 1 second and then CAL 0640 followed by CAL 0636. Are these some sort of diagnostic codes?

    Finally, as I said before, the MFD has not been lit for years so I don't remember what normal operation is but I thought I read that the display is supposed to go blank after 5 minutes or so. Mine stays lit with the following displayed:

    Fuel level, Oil level, Trim position, Time (whitch I never figured how to set) and under the Time the "RPM CLK DIST HOUR VOLT" mode indicators. Do I possibly just have a bad MFD? Should I just remove the fuse again and see if normal operation returns?

    Thanks in advance.


  6. #6
    She likes the bike. But the ski gets her wet!!!! xlint89's Avatar
    Join Date
    Oct 2006
    Cleveland OH
    Yes, it's most likely a bad float.

    You can get a replacement from john Zigler or Sharp's Marine for aorund $30.

    There's a bunch of info in the tech section to help you out. It includes how to reset your MFD. Check it out.

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