Fuel Leaking into and out of the airbox

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  • Stryfe

    #1

    Fuel Leaking into and out of the airbox

    1980 GS850GT, Just recently replaced the stator with an electrosport stator from bike bandit, also replace the regulator rectifier. But now all of a sudden out of the blue it's now leaking fuel back into and out of the airbox, could someone tell me what could be causing this. TIA
  • rustybronco
    Forum LongTimer
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    • Jul 2005
    • 14961
    • Marysville, Michigan

    #2
    Originally posted by Stryfe
    1980 GS850GT, Just recently replaced the stator with an electrosport stator from bike bandit, also replace the regulator rectifier. But now all of a sudden out of the blue it's now leaking fuel back into and out of the airbox, could someone tell me what could be causing this. TIA
    Carbs, fuel leaking past the needle and seat...
    This forum contains old posts which may have information which may be useful. It is a closed forum in that you can not post here any longer. Please post your questions in the other technical forums.


    take them completely apart and clean everything properly: lest you be doing them again.
    Last edited by rustybronco; 11-17-2008, 05:03 PM.
    De-stinking Penelope http://thegsresources.com/_forum/sho...d.php?t=179245

    http://www.thegsresources.com/_forum...35#post1625535

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    • bonanzadave
      Forum Guru
      Past Site Supporter
      • Jul 2006
      • 9623
      • Minnesota

      #3
      How much fuel ? If its more than a little your petcock diaphragm is leaking or its set on PRI.
      82 1100 EZ (red)

      "You co-opting words of KV only thickens the scent of your BS. A thief and a putter-on of airs most foul. " JEEPRUSTY

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      • Stryfe

        #4
        could it be stuck on Prime even if the lever is set to run?

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        • rustybronco
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          • Jul 2005
          • 14961
          • Marysville, Michigan

          #5
          Even if you ran a hose direct from the tank to the carbs, the fuel inlet valves will shut off the fuel flow if they are properly working.
          when you put the petcock in the prime position, the fuel will flow to fill up the bowls. then when the carbs are at the proper level, the fuel valves will stop the fuel from filling them further.

          I know it's not what you wanted to hear...

          you can check the petcock by pulling the fuel line off of it, then see if it's leaking fuel in the run position.
          Last edited by rustybronco; 11-17-2008, 07:27 PM.
          De-stinking Penelope http://thegsresources.com/_forum/sho...d.php?t=179245

          http://www.thegsresources.com/_forum...35#post1625535

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          • Nessism
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            • Mar 2006
            • 35788
            • Torrance, CA

            #6
            Sometimes when the petcock fails it dumps fuel down the vacuum line and into the engine. Check this as well as the float needles like rusty suggests.
            Ed

            To measure is to know.

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            • neal

              #7
              I had the same problem. Solved by adding new foam strips to the air cleaner housing so it had a tight seal and then sealed up the entire airbox from leaks.

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              • Guest

                #8
                Originally posted by neal
                I had the same problem. Solved by adding new foam strips to the air cleaner housing so it had a tight seal and then sealed up the entire airbox from leaks.
                You got leaky carbs to stop leaking by sealing the airbox?

                Is the bike running on all cylinders? Fuel will leak out of the carb when the cylinder is not firing.
                If not the likely suspects are leaky float needle and seats from dirt or being worn out and the petcock. Is it leaking when running or sitting?

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                • Stryfe

                  #9
                  It's leaking out the air box when it's running

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                  • Nessism
                    Forum LongTimer
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                    • Mar 2006
                    • 35788
                    • Torrance, CA

                    #10
                    Originally posted by Stryfe
                    It's leaking out the air box when it's running
                    and?...
                    Ed

                    To measure is to know.

                    Mikuni O-ring Kits For Sale...https://www.thegsresources.com/_foru...ts#post1703182

                    Top Newbie Mistakes thread...http://www.thegsresources.com/_forum...d.php?t=171846

                    Carb rebuild tutorial...https://gsarchive.bwringer.com/mtsac...d_Tutorial.pdf

                    KZ750E Rebuild Thread...http://www.thegsresources.com/_forum...0-Resurrection

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                    • Guest

                      #11
                      Are you running on all cylinders? Missing?

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                      • Stryfe

                        #12
                        no aslong as I keep the throttle applied it sounds like it's running fine, but at the same time leaking fuel out the airbox, as soon as I release the throttle it dies.

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                        • TheCafeKid

                          #13
                          You likely, but not for sure, have one of three things, or a combo of one or more happening:

                          Bad float valves: if the float valve has any indentation or a scoring ring on the needle, its no good and not sealing.

                          Improper float levels: this is very important. The floats are what shut fuel flow off when the carb bowls are full.

                          Bad petcock.

                          With the BS (cv) carbs, there is no overflow hole aside from the vents, which usually cant rid the carbs of excess fuel fast enough. Consequently, eventually, the fuel will fill up passed the needle, and leak down thru the throats into your airbox, and your crank case. This is bad for MANY reasons, aside from the obvious, and not fixing it will lead to long term damage.

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                          • bwringer
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                            • Oct 2003
                            • 17066
                            • Indianapolis

                            #14
                            I have found that the mung from the insides of an old, corroded petcock can make its way down to the float needles and prop them open.

                            A new petcock solved that problem.
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