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  1. #1

    1996 Fuji 780 Electric issues

    I found a nice 96 - 780 that the guy rebuilt the drive unit. It started right up in the driveway so off to the lake. Unfortunately I did not do a through walk around and he forgot to reconnect the water line that connects below the exhaust port. So luckily the red light go off I turned off the engine and tow it back to the ramp.

    When I got home I found a issue, I guess the water (it was above the battery) shorted it out and caused the black ground wire to get so hot it melted through the plastic sleeve. The wire was brittle but intact. I was able to get is started in the driveway. So with the hose connected it was off to the lake. I ran perfect (except for the low end - getting out of the hole - but that is a different discussion). it ran well for 3 full days 51-53 MPH then all of the sudden it died. After getting towed in again it does not seen to have any spark. I bought a spark tester and all 3 cyl are the same no spark. I opened the electric box and it looks brand new. Whats my next step? Do I need to replace the wire all the way to the magneto? I do have an extra one from a 94 - 750 that had 2 cyl with holes in them that I bought for body parts.

    PS I still get power to the read out in the handle bars.

    Thanks for the help.
    Last edited by K447; 09-07-2014 at 09:49 AM.


  2. #2
    Click avatar for tech links/info, donation request K447's Avatar
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    Is the plastic battery cover missing? If the battery shorts to the electrical box it will burn out the black wire to the stator. That black wire is critical for running the engine.

  3. #3
    The electrical box is mounted to a small blukhead? in front of the battery not on top of it like in my 750. the water was above the battery and 1/2 way up on the box.
    It does look like it is singed all the way. What is the best way to repair it?

    Some time we like to go to the bay at the ocean so I need to repair it the best way. Can I replace the entire stator and wire harness from the old 94 - 780 engine I have?

  4. #4
    Why would it work for 3 days then die?

  5. #5
    Do you know why the bilge pump did not keep the water out? I could not find a switch for it.

  6. #6
    Click avatar for tech links/info, donation request K447's Avatar
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    Quote Originally Posted by gwnkids View Post
    Do you know why the bilge pump did not keep the water out?

    I could not find a switch for it.
    Bilge pump is supposed to run continuously when the engine is running. It is powered by the LR module inside the electrical box. There is a 3 Amp fuse for the bilge pump.

    From 1997 onwards there is a Bilge switch on the handlebar to manually run the bilge pump. 1996 models did not have the Bilge switch, but it can be retrofitted.

    Which 780 model do you have, SL or SLT?

    I suggest you need to go through this watercraft from end to end and check everything.
    See my signature links for recommended maintenance and upgrades.

    Do not simply fix the few things that seem obviously broken right now. The machine is eighteen years old. You cannot assume the previous owner maintained it well or even knew about everything that needs maintenance.

    Seals and bearings slowly wear and become more likely to fail completely. Carburetors and the entire fuel system accumulates crud and hoses get stiff, rubber parts weaken from age. Even if an old part is working today does not mean it will continue working a few hours or weeks from now.

    It takes effort to make an older watercraft, of any brand, reliable. Reliability comes from actually doing the inspections, rebuilding parts that are expected to wear or age, and upgrading those things which have been identified as weak points.

    The cost of doing the work will vary. The cost of not doing it is a much higher risk of additional failures while you are on the water. Being stranded in the water is no fun and there is a real risk to personal safety if the watercraft fails while you are away from shore and not near help.

  7. #7
    Good deal
    780 SLT
    I did a continuity test - Battery ground to the spark plug hole and all 3 are OK I get tone.

    Do you recommend pulling the engine? Is there a step by step start at A first then end at Z list?
    it has 140 in each cyl.

  8. #8
    Click avatar for tech links/info, donation request K447's Avatar
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    Quote Originally Posted by gwnkids View Post
    Good deal
    780 SLT
    I did a continuity test - Battery ground to the spark plug hole and all 3 are OK I get tone.

    Do you recommend pulling the engine? Is there a step by step start at A first then end at Z list?
    it has 140 in each cyl.
    Battery must be disconnected for valid tests of ground wiring integrity.

    Use ohms mode, not continuity. Burned wires can sometimes have partial conductivity but are not a solid zero ohms connection.

  9. #9
    good point - no battery and everything ohm at 0
    used the battery ground wire and touched all 3 cyl.

  10. #10
    Click avatar for tech links/info, donation request K447's Avatar
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    Quote Originally Posted by gwnkids View Post
    good point - no battery and everything ohm at 0
    used the battery ground wire and touched all 3 cyl.
    Start checking stuff. Stator coil ohms tests are posted via my signature links. Same with ignition coils and spark plug wires.

    Make sure the grounds inside the electrical box are all good. There may be a black wire between the two halves of the box.

    There is a grounding bolt for the negative battery cable at the engine. This is not actually the engine, it is the engine bed plate. Sometimes the engine bed plate is not well grounded to the actual engine case. There are bolts underneath the engine that can corrode or become loose. Sometimes the paint and accumulated corrosion cause the ground to be weak.

    A work around is to move the battery cable to the engine itself. One spot is the intake manifold stud for the PTO cylinder. Another is right on the mounting bolt for the starter motor. Harder to get at while the engine installed but provides a very direct and solid grounding point.
    Last edited by K447; 09-05-2014 at 05:53 PM.

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