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  1. #1

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    96 Polaris slt 780 ignition problems

    hey, so i have a 96 polaris slt 780 i bought off a guy last week who was really motivatied to sell. Ran it this weekend and it fired up and ran but kinda felt slow and slugish like not firing on all three cylinders then every now and then it would kick in and take off running faster like it should. Then slow back down again. This went on and on all day. Any ideas?

    -So the next mornig it won't start, know its getting gas, pull plugs out and no spark. So just brought it back home. Did some research today and tested the stator, cdi, and coils. Obviously someone else has been inside this box before, lets just say there was some 'jerry riggin' goin on it was a little messy but look like everything was hooked up. Stator tested good but think my cdi is messed up. Now I can get a very weak spark out of the first and third plug but none out of the second. I was wondering if I am on the right track here? And if anyone has a cdi for sale or where I can get one?

    Thanks for any help.


  2. #2
    Bing-A-Ding-Ding-Ding, Brrrrrap! Brrrrrrrrrap!!! Polaris_Nut#1's Avatar
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    Might be on the right track, got any pictures? how does the back of the circuit board look? I had one that was rusting a part and needed replacing.

  3. #3
    BlueFishCrisis's Avatar
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    The CDIs fire all three plugs at the same time. I would check to be sure you have a clean contact at the plug boots by unscrewing them and cutting the plug wires back 1/4", then reattaching. Also make sure your motor baseplate ground is solidly attached. What kind of plugs are you using? Gap?

  4. #4

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    The plugs new, put some in it right before I took it out, they are NGK BR8ES same that came out of it. I gaped them to some specifications I saw on this forum the other day but now I forgot what it was. I cheked the resitance through all plug wires and boots, even pulled the boots off and trimed them back like you said. They all checked good. Looking at the circuit board its not really rusting. Had a little corrosion on a few terminals that I cleaned off. I'm thinking i need a cdi box and maybe the secondary coils too. From what I found online so far they are like over $200 used. Does anyone know where I can find some cheaper or atleast new for that price.

  5. #5
    BlueFishCrisis's Avatar
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    Look for someone on here parting out a ski....

  6. #6

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    - Hey, so I'm still having some problems. Got a used cdi box and coils off a guy and tried hooking them up. Still no spark. So I started to just mess around with it today and heres what I'm finding out. If I hook the cdi box up and one coil I get excellent spark at the plug. Now if I go back and hook another coil up, in series with the first one, I get spark out of both wires fine. The problem is when I hook the third coil up, then I lose spark on all three wires. Does anyone think That if I were to go in a hook all the coils up parallel like instead of series it might help? Also I have two cdi boxes now and six coils, I've tried about every different combination of coils and box and still get the same result, spark with two coils, go three and nothing. Also is this an indication of a stator on it's way out? When I test it with my meter off the wiring diagram everything seems to be fine and within the right perameters. Any ideas are greatly appreciated, thanks.

  7. #7
    Click avatar for tech links/info, donation request K447's Avatar
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    The common elements (things that are the same in all your tests);

    Stator
    Grounding wires and connections
    Electrical box terminals and other connections
    Spark plugs
    Plug wires
    ...
    Technition

    It seems likely that one or more of these is the cause.

  8. #8

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    Alright, after further trial and error today I finally have spark at all three pulgs. Then I go to start it and can only get it to run for a second if I pour gas down the carbs. Unhooked the individual gas lines on each carb and sure enough not getting any fuel. Is there an electronic fuel pump in the gas tank? I have a pink and black wire running down in the tank at the pickup tube and I was wondering if there is a fuel pump down there and if there is any way to test it or turn it on. I unscrewed the bowl and dumped out the gas from in it, now there is pretty much no gas in my fuel lines anywere. Is there a way to prime this system back up? or with all my monkying around in there lately can you guys think of something obvious that would cause this?

  9. #9
    Click avatar for tech links/info, donation request K447's Avatar
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    There is no electric fuel pump in a Polaris carburetor watercraft.

    The fuel pump is pneumatically driven by the crankcase air pressure pulses. There is a pulse hose on the side of the engine that connects to the fuel pump. Make sure the fuel pump hoses are all connected properly, and the fuel selector valve is turned on.

    And there is enough fuel inside the fuel tank

  10. #10
    BlueFishCrisis's Avatar
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    No fuel delivery points to multiple possible causes. Is your fuel sender intact and fully operational? May need to pull it out of the tank and make sure it is in one piece and not clogged. Fuel lines should all be free and clear, highly recommended to replace. Fuel select switch must be in good operating condition so as to not let air leaks in, all hose clamps / fittings must be tight to not let air in. Fuel pump must be in good working order, recommend rebuild at this age. Fuel water separator filter screen must be clean and free of debris, fuel pump pulse line must be free and clear without debris or fluids from motor crankcase to fuel pump pulse fitting, pulse fitting on motor crankcase must be free and clear without any debris or fluids, there must not be any fluid on pulse side of fuel pump.

    What are your compression readings for Mag, Cen, and PTO in PSI? The fuel pump will not properly operate without a good strong pulse from the bottom half of the PTO piston. This is directly related to compression. Are your reeds in good condition? This will also affect crankcase pulse operation.

    Alot to look at.......

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