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Fuel flowing from breather pipe

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    #1

    Fuel flowing from breather pipe

    The bike is an 81 GS850G. The problem is fuel flowing from the breather pipe (the only name for the hose I could find in the Haynes Manual). It is the hose coming from the top of the carbs to the air box. Any suggestions as to what could be the problem(s)?

    This happened last season and I took it to a mechanic who worked on the carbs and put new rubber between the air box and carbs. I drove about 100 miles and it happened again.

    Thanks,

    Mike
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    #2
    Re: Fuel flowing from breather pipe

    There are no hoses connecting the carbs to the airbox. There is one valve cover vent hose (about 5/8" diameter) that connects to the front, top, center of the airbox. Is that what you mean? Carb fuel lines are 5/16" and carb vacuum lines are 1/4".

    Earl


    Originally posted by Montana Mike
    The bike is an 81 GS850G. The problem is fuel flowing from the breather pipe (the only name for the hose I could find in the Haynes Manual). It is the hose coming from the top of the carbs to the air box. Any suggestions as to what could be the problem(s)?

    This happened last season and I took it to a mechanic who worked on the carbs and put new rubber between the air box and carbs. I drove about 100 miles and it happened again.

    Thanks,

    Mike
    Komorebi-The light filtering through the trees.

    That human beings can not bear too much reality, explains so much.

    Comment

      #3
      Fuel flowing from breather pipe

      Earl,

      You are correct. I misspoke.

      Mike

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        #4
        It sure sounds like you have a sticking float and/or needle , and this is allowing fuel to flow , which is overflowing into the airbox, BTW check your oil level as it is as likely that at least some has run into the cylinders and past your rings.
        Dink

        Comment

          #5
          Dink,

          What you said is one option. The other is a bad petcock on the gas tank. Whichever it was, I think the fuel flowed into the crankcase and was forced up through the valve cover area and thus through the breather tube. Now I'm watching the oil level window very carefully.

          Thanks for the reply,

          Mike

          Comment

            #6
            I can't believe that you could fill up the airbox with enough fuel for it to top the airbox and have it run into the camcover breather hose.

            Are you talking about the carb vent lines: one between carbs 2-3 and one between carbs 3-4. Those hoses run to sit on top of the airfilter box.

            Comment

              #7
              The fuel (oily and foamy) was flowing from the hose that connects to the top of the air box. The Haynes manual identifies the hose as the breather hose. After this happened, the crankcase was full to overflowing with fuel.

              This happened twice. The last time a friend took apart the petcock and turned over a rubber o-ring (That's what he said. I've never taken apart the petcock.) and the problem seems to have gone away. If it happens again when the bike hasn't been running, I'll know the culprit is the petcock. If it happens when the bike is running I'll surmise it was needle valves not seating or a stuck float. Now I check the oil level window every time I start the bike.

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