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Thread: Bogging down

  1. #1

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    Bogging down

    I just purchased a 1998 Polaris SLTH 700, I have had it for a couple of days and when I got it it was running great it had a half tank of gas in it. After riding it a while I put more gas in it, immediatly after putting gas in it came my problem. When I start it and take off everything is normal and I have WOT for about 2 minutes and then it will not rev over 3200 rpm unless I stop in the water and wait a few seconds then it will take off again but only for a few seconds there are no warning lights on the display. But if I park it in my slip and wait an hour and go try it again it runs great for a few minutes then boggs again. I have changed the plugs and cleaned the carbs any idea what I should do next? This is very annoying I have read quite a few threads with similar problems and am thinking maybe the CDI box or the LR54 Module. But nothing has gotten wet inside since I have owned it. and it was running great before the new gas. Does anyone have any suggestions? I am going to have a compression test done this weekend. Also Moving the Choke does not help the problem and it will die if I open it all the way, So I am convenced it is not fuel. I also might add that this problem didn't happen all of a sudden at first it would get to about 30mph then decrease and then 20mph etc. Let me know what you think. Thanks


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

    I presume you have found the Polaris Service Manuals here.

    Does you model have the MFD digital display?

    Unplug the Gray wire from the LR-54 module inside the electrical box. Does that fix the problem?

    Is yes, then something is causing the RPM limiter to engage. This is usually overheat, or low fuel.

  3. #3

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    yes it has the digital display and everything looks normal showing 3/4 tank of gas and oil with no warning lights. Not to sound dumb but what is the LR54 module and what is the CDI I am still new to this. Thanks

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    Quote Originally Posted by puffinbarger View Post
    ...what is the LR54 module and what is the CDI
    I am still new to this...
    The Service manual provides a lot of good info.

    CDI is the ignition module.

    LR is the voltage regulator module, and it also controls other functions like RPM limiting on some models, and switched power to the bilge pump.

    You model may have two LR modules, with the functions split between the two.

  5. #5

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    I did look through the service manual and like I said I am stil kinda new to wrenching with them so there where some parts that didn't make since so I assume the the grey wire I am supposed to unplugg is under the seat and inside the box where my plug wires go to?

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    Quote Originally Posted by puffinbarger View Post
    ...I assume the gray wire I am supposed to unplug is under the seat and inside the box where my plug wires go to?
    Yes, the electrical box is down behind the engine, and contains all the electrical components.

    You can find useful parts diagrams here.

    Disconnect the battery negative wire while you are working inside the electrical box. Make sure you re-seal the box and strap it back down before test riding.

    Also make sure the plastic battery cover is in place. If the battery terminals short to the box casing, it can cause a short circuit and damage the wiring.

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    Ok I will try unplugging the grey wire as soon as I get home today and see if that changes anything, If it does what does that mean that needs to be replaced?

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    Quote Originally Posted by puffinbarger View Post
    Ok I will try unplugging the grey wire as soon as I get home today and see if that changes anything,
    If it does what does that mean that needs to be replaced?
    Possibly the LR-54 module.

    I would want to check that the Tan overheat light/warning is actually working on your machine. If the overheat sensor was disconnected from the MFD, but still connected to the LR module, then an overheat could be happening (and triggering the RPM limiter), and you might not know.

    When the engine is running in the water, even after a high speed run, you should be able to put your hand on the engine cylinder heads for a few seconds without pain. Something like 1-2-3-4 that-is-long-enough!

    If you cannot touch the engine without burning yourself, it is too hot. Same for the water jacketed exhaust pipes.

  9. #9

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    the engine is not really getting hot at all I can place my hand on it for longer then that and its really not hot. If unplugging this grey wire helps will it hurt to leave it unplugged ? Does it just enample this safe mode feature to limit rpms?

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    Quote Originally Posted by puffinbarger View Post
    the engine is not really getting hot at all I can place my hand on it for longer then that and its really not hot.

    If unplugging this gray wire helps will it hurt to leave it unplugged ?

    Does it just enable this safe mode feature to limit rpms?
    It is better to fix the problem, and not just leave the gray wire unplugged.

    If you leave the gray wire unplugged, then if at some later time the engine does begin to overheat or fuel gets low, you will not have the protection of the RPM limiter.

    It is easy to ingest some mud or sand into the cooling system, and rapidly raise engine temperatures from the clogging and reduced water flow.

    Running the machine at high speed with very low fuel can aerate the fuel entering the fuel lines, which can cause lean burn damage to the engine. By limiting RPM, the engine is less sensitive to the air in the fuel, and the fuel tank is not being shaken as much, also reducing the chances of getting air into the fuel pick up.

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