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1995 Polaris SLT 750 with Fuji Engine - No Spark Issue

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  • 1995 Polaris SLT 750 with Fuji Engine - No Spark Issue

    Hi all,

    First post, so please let me know if there is anything that is not appropriate. Thanks.

    My Polaris lost compression on the mid cylinder 5 years ago and parked since then. We pulled it and installed a new battery. The guy did not install it carefully, so he shorted out the electrical box with the positive side of the battery. The result was burning out the ground wire from the electrical box to the stator and no spark even the Blk/Yel wire from the CDI had been isolated.

    I managed to replaced the ground wire and carefully measured the resistance of the following:

    Stator wires:
    - Red/Pur -- Yellow: 0.6 Ohms
    - Wht/Yel -- Black: 212 Ohms
    - Blu/Red -- Red/Wht: 89 Ohms
    - Red/Wht -- Grn/Red: 489 Ohms

    Ignition coil wires:
    - Blk - Blk/Wht: 0.5 Ohms
    - Blk - Thick Blk wire (to spark plug): 3.3 kOhms
    - Spark plug cap: 5.5 kOhms

    I removed all spark plugs from the engine and the CDI box from the electrical box, so I could measure the voltages between wires while cranking the engine
    - Battery not cranking: 12.89V (Fully charge)
    - Battery during cranking: 11.98V
    - Red/Wht -- Green/Red: 90VAC
    - Blu/Red -- Green/Red: 190VAC
    - Red/Wht -- Blu/Red: 18.6VAC
    - Yellow -- Red/Purple: 5.2VAC

    While the CDI box was unplugged, I measured the resistance between its wires:
    - Blk -- Blk/Wht: 0.2 Ohms (shorted together)
    - Blk/Yel -- Blk/Wht: resistance started at 133 kOhms and slowly dropped and stopped at 58 kOhms
    - Blk/Yel -- Blk: resistance started at 10 kOhm and slowly increased and stopped at 58 kOhms
    - Red/Wht -- Blk (or Blk/Wht): open
    - White -- Blk (or Blk/Wht): 9.8 kOhms
    - Green/Red -- Blk (Blk/Wht): 477 kOhms
    - Blu/Red - Blk (Blk/Wht): 453 kOhms

    I read all posts that related to "1995 Polaris no spark", and I could conclude that my CDI box might be bad because of the shorting out of the electrical box with the positive side of the battery. However, I just want to have your expertise since I am not very familiar with this ski.

    I can measure the voltage more precisely on an oscilloscope if necessary, so please let me know.

    Thank you much for reading my first post and helping me.
    Attached Files

  • #2
    Welcome to the Hulk.

    First, did you install the lanyard?

    Have you verified the kill switch is not causing you issues by removing it from the circuit board?

    Do you have the ground jumper wire installed in the elec box? It goes from the starter solenoid grounding location to the ground buss on the other half of the box. And that goes to the magneto.

    Is your ground cable connection clean and tight on the engine mounting plate?

    If everything checks out good, you might have to replace the CDI. There is no test for the CDI, you eliminate everything else, and when they check out, you replace the CDI.
    My ski says made in the U.S.A...... Can yours say that???


    • #3
      Hello Xlint89,

      Thanks for your advice.

      Yes, I did tried with the lanyard in place. I even pulled the Blk/Yel wire from the CDI box out of the circuit, but there is still no sign of spark.

      Engine ground should be very good, and I even tested to see the spark right at the electrical box GND bolt.

      I downloaded the service manual, but no part in there to mention the output voltages of the stator coils.

      The CDI is very expensive either on Ebay or Amazon, and I want to be sure that it has a problem before buying a new one.

      Again, thank you


      • #4
        I would avoid any CDI sold on Amazon. They seem to be hit or miss with aftermarket electronics. I'd try to source a good used OEM before purchasing a new aftermarket.

        You're in Houston I see, I wonder if anyone near you can lend you one for testing purposes? You're going to know if it's the CDI right away and pretty easy to swap in/out.

        I'll be perfectly honest with you, K447 can speak electronicease with the best of them. I would have just swapped out the magneto and the CDI first. It's most likely one if not both of them, and spare parts is always nice to have if they weren't needed.

        Just for chits and giggles, try disconnecting the MFD and see if that helps? It shouldn't, but some have reported the MFD causing issues.
        My ski says made in the U.S.A...... Can yours say that???