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  1. #1

    Unhappy hard to start, bogs and dies

    I just got my 96 780sl running great after a problem with the cylinders filling with fuel. Then in a rain storm ( machine was in the water) the engine cavity filled up with water. since then it is very hard to start and when I do get it going it chugs for 3-5 minutes ( just enough to get me too far from the dock) then dies. If I let it sit for a few hours with the fuel selector off ( good advice from the hulk) it will start and then die again. I have put in new plugs and same results.

    What should I try next?

    Thanks
    Ekmols


  2. #2
    bowsniper's Avatar
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    what do you mean filling with fuel?

  3. #3
    She likes the bike. But the ski gets her wet!!!! xlint89's Avatar
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    Have you checked inside the elec box?

    Shouldn't be any water or corrosion.

  4. #4
    I will check out the electrical box, although it seems to be getting a spark, maybe not consistent, Early this spring the cylinders would fill up with fuel if it sat for a while between runs. It was K447 who suggested I put in a new check valve on the fuel vent line and shut the fuel selector off after each run. That seemed to solve that problem. The fuel would shoot up about 10 feet from the open spark plug holes when I cranked it over. I dried it out by cranking it and spraying compressed air in each cylinder.

    It ran great for a short while, now this new problem. It seems you have to be a pretty good mechanic to keep these old machines running. Last season I had to have the starter rebuilt and make some modifaction to the rear end to fit the newer model steering cable. Mine snapped and the local dealer said they don't make them for your year any more.

  5. #5
    She likes the bike. But the ski gets her wet!!!! xlint89's Avatar
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    These 14 year old skis will keep you on your toes.

    However, doing the work yourself will save a ton of $$$$.

    Double check your battery cables are clean and tight, as well as your ground connection at the engine plate.

  6. #6
    bowsniper's Avatar
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    I bet the diaphram in one of your carbs is junk and letting fuel into the cylinder. that fuel pump pumps fuel at 65/litres an hour! . thats 1.1 litres per min! enough to fill the cylinder to the top in 1 min free flowing.

    If it was a Pro785 with dual pumps, the fuel just pours into the cylinders if the pump on 1 side is bad. . you can see it pouring in. enough to fill a cylinder.

    I know this because it happend to me 2 days ago. i rebuilt the pump and it works fine now..

    do you live in a hot area? the vents could be clogged...creating the pressure your describing.

    Try new plugs. if you had that much fuel in the cylinders, they are fouled for sure..

  7. #7
    She likes the bike. But the ski gets her wet!!!! xlint89's Avatar
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    Quote Originally Posted by bowsniper View Post
    I bet the diaphram in one of your carbs is junk and letting fuel into the cylinder. that fuel pump pumps fuel at 65/litres an hour! . thats 1.1 litres per min! enough to fill the cylinder to the top in 1 min free flowing.

    If it was a Pro785 with dual pumps, the fuel just pours into the cylinders if the pump on 1 side is bad. . you can see it pouring in. enough to fill a cylinder.

    I know this because it happend to me 2 days ago. i rebuilt the pump and it works fine now..

    do you live in a hot area? the vents could be clogged...creating the pressure your describing.

    Try new plugs. if you had that much fuel in the cylinders, they are fouled for sure..
    What are you talking about?????

    How does a bad diaphragm let fuel into a cyl? Please explain this....

    Can you also explain how a triple outlet fuel pump can deliver 65 liters of fuel an hour to 1 cyl with the engine not running?

    Let me get this one straight....

    If 1 fuel pump on a PRO 785 goes bad, the other 1 works twice as hard, and pushes fuel past the needles and seats, and just fills up cyls?

    And alot of fuel in a cyl will foul a plug for sure??? How?

  8. #8

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    65 liters/hour???? You kidding? That means the ski could run for about 45 minutes before the tank is empty.

  9. #9
    She likes the bike. But the ski gets her wet!!!! xlint89's Avatar
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    Quote Originally Posted by xlint89 View Post
    What are you talking about?????

    How does a bad diaphragm let fuel into a cyl? Please explain this....

    Can you also explain how a triple outlet fuel pump can deliver 65 liters of fuel an hour to 1 cyl with the engine not running?

    Let me get this one straight....

    If 1 fuel pump on a PRO 785 goes bad, the other 1 works twice as hard, and pushes fuel past the needles and seats, and just fills up cyls?

    And alot of fuel in a cyl will foul a plug for sure??? How?







  10. #10
    followed the posted advice and got the machine running well in a short test drive. Did not take it out too far as no one was around to assist if It died again. Seems to runnig fine , will confirm this week end with some serious riding

    Thanks to all

    Ekmols

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