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  1. #1

    96 780 success and need your input

    Ok, I have a 96 780. Wouldn't run or if it did it wouldn't idle and was extremely hard to start. but curiously when it was cold it would start just fine on land on the trailer but not in the water.

    So I followed the advice given here; new good quality battery, new plugs, rebuilt the 3 output hex fuel pump and changed all the fuel lines. Also made sure the in and the out vents on the fuel tank worked and the fuel strainer separator bowl was cleaned out. Also, it had lower octane fuel in it, maybe less than a quarter tank. I then filled it up all the way with 93 octane and included a can of Gumout. I did all these things so I knew where I was at with fuel but I did not see anything wrong with the fuel lines internally or the fuel pump internals. But I am glad I did it all anyway.

    Started it up and after fuel filled the lines it started. What it did though is race way up I mean way up! I turned the idle screw down 1 turn and started it up again, it was idling too low. I turned the idle up 1/2 turn and everything was great. So net adjustment was that I turned it down 1/2 turn. Next it went in the water and I drove it for 2 hours and it ran great. Idles great top speed is where it should be. The only thing is that there is a little hesitation when I give it full throttle from idle. but no big deal.
    2 Questions:
    My father says there was nothing wrong. it just needed the higher octane gas and the gumout.
    I don't know but to me if that was all it was, why did it race up causing me to have to back off the idle 1/2 turn? My dad thinks I inadvertently turned the idle screw with my arm while trying to get the fuel pump mounted. (he always has an answer)
    I'm happy, but it is good for me to know what made the difference. What do you guys think made the difference?
    What can I do to fix the hesitation if I want to do it?
    Thanks in advance for your input!


  2. #2
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    You can try backing out the low speed screws a touch, try 1/8 turn at a time.

  3. #3
    She likes the bike. But the ski gets her wet!!!! xlint89's Avatar
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    Sorry, but higher octane fuel and Gumout prob. did nothing. Fresh gas maybe????

    Gunout will not clean the varnish that forms inside your carbs from sitting, and higher octane fuel is actually harder to burn than lower octane. (although you should use 89 octane or higher when fuel is oxygenated per Polaris recommendation)

    Your fuel pump may have been weak, or had some kink in the fuel line or something like that.

    Your motor raced because the engine was starving for fuel. Most likely due to the fuel lines being new and needing to be primed, or just because you're out of ther water. They run around 3600 RPM when on the trailer, but around 12-1300 RPM in the water. That's why you set the idle in the water.

    You'll prob get rid of the low end bog if you rebuild the carbs if you haven't already.

    Tell dad sorry, but 2 stroke watercraft are not 4 cycle cars with dirty valves or injectors that can be cleaned over time by using additives to the fuel.

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