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Thread: fuel lines

  1. #1

    fuel lines

    I have a 96 780SL. and the cylinders are filling up with gas if I forget to shut the fuel line selector to off. This happens often enough as a few different people take this machine for a drive. I put in a new check valve on the vent line, but I still get a lot of hissing when a loosen up the gas cap. Gas will also keep pouring out of the water seperator when I remove it as well. It then takes me a couple of hours to blow the gas out of the carbs and cylinders with a compressor.

    Any ideas on how I can spend more time riding and less time trying to start this machine.

    Thanks

    Ekmols


  2. #2
    ujustlost's Avatar
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    Quote Originally Posted by ekmols View Post
    I have a 96 780SL. and the cylinders are filling up with gas if I forget to shut the fuel line selector to off. This happens often enough as a few different people take this machine for a drive. I put in a new check valve on the vent line, but I still get a lot of hissing when a loosen up the gas cap. Gas will also keep pouring out of the water seperator when I remove it as well. It then takes me a couple of hours to blow the gas out of the carbs and cylinders with a compressor.

    Any ideas on how I can spend more time riding and less time trying to start this machine.

    Thanks

    Ekmols
    The hissing when you open the gas cap is normal. The cylinders fill up with gas or just the bottom end of the motor?

  3. #3
    The cylinders and Carbs fill up, if I crank it over with out the plugs in the gas spurts up over 10 feet in the air, I got a face full of gas and oil the first time.

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    blegan's Avatar
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    Sounds like water, I couldnt imagine that much fuel back flowing through.

  5. #5
    Click avatar for tech links/info, donation request K447's Avatar
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    Quote Originally Posted by ekmols View Post
    I have a 96 780SL. and the cylinders are filling up with gas if I forget to shut the fuel line selector to off.

    This happens often enough as a few different people take this machine for a drive. I put in a new check valve on the vent line, but I still get a lot of hissing when a loosen up the gas cap.

    Gas will also keep pouring out of the water separator when I remove it as well. It then takes me a couple of hours to blow the gas out of the carbs and cylinders with a compressor.

    Any ideas on how I can spend more time riding and less time trying to start this machine...
    Which check valve, or both?

    Did you install it the right way around? There is a direction to these vent check valves.

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    ph2ocraft's Avatar
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    Check your pop off pressure, the needle/seat assembly may not be sealing and allowing the fuel a direct unrestricted path to the engine.

  7. #7
    I only replaced one check valve as this was all I found. it is on the line that goes from the top of the tank to the vent on the hood by the steering consule. I am not sure what the pop off pressure is and how to check it.

    It is gas that is filling up the cylinders, not water

  8. #8
    Click avatar for tech links/info, donation request K447's Avatar
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    Quote Originally Posted by ekmols View Post
    I only replaced one check valve as this was all I found. it is on the line that goes from the top of the tank to the vent on the hood by the steering consule...
    Your vent system should look like this.

    Items 4 and 20 are the vent valves.

    Valve 4 vents OUT from the tank, and the small arrow on the valve body must face upwards.

    Vent 20 vents IN to the tank.




    Click here for the Polaris Industries parts cross reference guide

  9. #9
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    Wow you have a gusher! A probability is that your fuel tank will burst/pop if you dont fix that way over pressure problem.

    The fuel pressure relief valve at the fuel tank seems not to be working. On Backwards? Thats a whole lot of gushing to be flying out your spark plugs holes.....................

    Compressor? How do you that? where?

  10. #10
    ripcuda's Avatar
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    Quote Originally Posted by la90043 View Post
    Wow you have a gusher! A probability is that your fuel tank will burst/pop if you dont fix that way over pressure problem.
    ...
    Compressor? How do you that? where?
    The gusher is from when he cranks over the engine with plugs out (not tank pressure)... it will squirt big time any fluids in there.

    By compressor I'm guessing he's using an air compressor and blowing air into the carbs and spark plug hole to dry out the flooded cylinders.

    ....
    I also think it sounds like the fuel tank relief valve. My '94 SLT which was "shop maintained" during previous ownership, had the stock single vent upgraded to the dual (in and out) vents as seen in the pic above. The out vent (#4) was on backwards. They were both only letting pressure in. D'oh!

    So I notice that the out-vent has a higher cracking pressure... you gotta put a few psi behind it before it vents. Verses the in-vent which lets air by with hardly any pressure. They are obviously different designs.

    What's the logic for the out-vent holding more pressure before it vents? Minimize atmosphere killing gas fumes?
    Anyone know the rated pressure for this vent?


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