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  1. #1
    PWCToday Guru
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    SLT 780 wont run over 4000 rpm-Hitting limiter???

    hi Guys I have a little Question hopefully you Polaris Guru's have plenty of experience on these Blue Fuji Engines.
    Its a 97 SLT 780 3 seater
    the engine Compression is perfect The reeds are pefect. The carbs are perfect.

    The engine doesn't want to rev over about 4000rpm. I haven't put a tacho on it , but I'm somewhere close. I went and put a whole new(second hand freshwater excellent condition) electrical box in it to hopefully solve problem. Guess what. It still only revs to about 4000rpm. Its certainly hitting a limiter somehow.Its an electrical issue. I actually work and rebuild heaps of skis just not many polaris's, so I'm good with 2 strokes.

    Now the Display dash does not work on this ski.It has faded and gone berko!. I tend to think this may be the problem. Perhaps??
    I have disconnected the gray wire to the CDI and it still revs to only 4000rpm
    Any advice from you guys would be great. Id like to get running and sold to a happy customer. Thanks

  2. #2
    PWCToday.com Is My Home Away From Home Tom V's Avatar
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    Re: SLT 780 wont run over 4000 rpm-Hitting limiter???

    Disconnect the gauge and see what happens.
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  3. #3
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    Re: SLT 780 wont run over 4000 rpm-Hitting limiter???

    Quote Originally Posted by Tom V View Post
    Disconnect the gauge and see what happens.
    Thats an idea!
    I'll give it a go
    ta

  4. #4
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    Re: SLT 780 wont run over 4000 rpm-Hitting limiter???

    I checked the gauge and found the 6 pin plug had already been disconnected. .I reconnected it and re tested it. Still keeps hitting rev limiter.at about 4000 rpm
    having found the amount of wires to go to the gauge and return to the electrical box- kind of tells me thats the problem. Does anyone know a way to by pass this and what wires to jump or disconnect.
    Thanks

  5. #5
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    Re: SLT 780 wont run over 4000 rpm-Hitting limiter???

    Did you figure this out? I have a 1996 slt780 doing the exact same thing and I want to sell it as well!!

  6. #6
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    Re: SLT 780 wont run over 4000 rpm-Hitting limiter???

    Quote Originally Posted by fozziez28 View Post
    Did you figure this out? I have a 1996 slt780 doing the exact same thing and I want to sell it as well!!
    Well you know what.
    I haven't fixed it. Its a Shame as it maybe a simple 5 minute fix if someone with alot of Polaris Experience could help. As I understand it happens to alot of Polaris jetski's.
    I put a Dash -MFD in it as the current one wasn't working(Luckily I borrowed it and didn't pay for one) This didn't fix it. it has a whole new electrical box in it-no change.

    It has to be a sensor on either oil,Fuel ,or over heat that is Jamming on. I would just love to know what to dissconnect on the circuit board to somehow by-pass this problem.
    i have spent about 3 hours trying to ground sending unit wires and just unplug from the circuit board. whatever I seem to do it still wants to limit at around 4000 rpm.

    What is a pain in the *** is someone out there knows the simple fix. They just havent read this Thread yet .If you find out let me know???.I really dont want to part ot out. As motor etc is in great shape. Would be a nice buy for $1000 on trailer for someone.


    Any more help Peoples,, Ex Polaris Mechanics??????????????

  7. #7
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    Re: SLT 780 wont run over 4000 rpm-Hitting limiter???

    have you tried swapping out the sensors? I am going to try the gauge thing first as I haven't tried that. Try switching the oil sensor, fuel sensor and the temp sensor and see if it fixes it. If you switched electrical boxes with one that was known to be good then that can't have been the problem. I switched cdi's and still didn't fix it. I am going to try and swap the sensors and see if that fixes it. I will let you know.

  8. #8
    Frequent Poster Keith447's Avatar
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    Re: SLT 780 wont run over 4000 rpm-Hitting limiter???

    Quote Originally Posted by nz253 View Post
    ...It has to be a sensor on either oil,Fuel ,or over heat that is Jamming on.

    I would just love to know what to dissconnect on the circuit board to somehow by-pass this problem.
    i have spent about 3 hours trying to ground sending unit wires and just unplug from the circuit board. whatever I seem to do it still wants to limit at around 4000 rpm...
    The only RPM limiter on the Polaris 1997 SLT780 is for engine overheat.

    The MFD display does not trigger the RPM limiter, it only lights the red warning lamp when the Tan colored Temp sensor wire is grounded.
    In normal operation, the temp sensor wire is an open circuit.

    To disable the RPM limiter find the Tan wire running from the Temp sensor to the electrical box, and disconnect it inside the electrical box.

    If that doesn't fix it, then disconnect the Tan wire that goes into the CDI module.

    If it is still RPM limiting, the CDI module may be bad.

    Make sure the correct resistor type spark plugs are installed. Non-resistor plugs can cause weird ignition problems.

    Also make 100% sure the black ground wire from the electrical box to the stator is actually grounded to the engine block. Disconnect the battery negative wires, separate them, and then check ohms from each to the engine block, and to the electrical box black wires.

    And make sure the CDI ground is really solid.

    Have you checked that all ignition coil and stator coil ohms are in spec?
    Click here for more help ==> www.greenhulk.net


  9. #9
    Frequent Poster Keith447's Avatar
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    Re: SLT 780 wont run over 4000 rpm-Hitting limiter???

    Quote Originally Posted by fozziez28 View Post
    ...I have a 1996 slt780 doing the exact same thing and I want to sell it as well!!
    The 1996 SLT 780 limits RPM for both engine overheat and Low fuel level.

    Do you have a red warning lamp on the MFD display, or Low Fuel or HOT messages?

    The 1996 SLT 780 electrical box uses an LR-54 module to control RPM limiting. The Gray wire from the LR-54 to the CDI is what actually activates the RPM limiter. Unplug the gray wire. If the RPM limit goes away, then check the overheat (Tan wire) and low fuel level (Pink wire) signals.

    Do not just leave the gray wire unplugged.
    If the engine really does overheat, there would be no warning, and no RPM limit, and the engine could be damaged.
    Click here for more help ==> www.greenhulk.net


  10. #10
    PWCToday Regular
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    Re: SLT 780 wont run over 4000 rpm-Hitting limiter???

    it might think its over heating look on the water rail for a switch torwards the back jump it .. might be in limp mode

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