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Thread: Signs of fuel in petcock vacuum pipe.

  1. #1
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    Fort Myers FL, New Tripoli PA or UK
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    Default Signs of fuel in petcock vacuum pipe.

    I've recently run the bike up a few times after a rebuild using a remote fuel tank to visibly check to leaks & balance the carbs etc., whilst doing so I had the petcock vacuum pipe on carb #3 plugged with a bolt. When I removed the bolt ready to connect to the petcock once the tank had been refitted I noticed it seemed to be moist with fuel, not running/dripping out but visible, in the end of the pipe. Is this normal & nothing to worry about or something that needs checking out ? Thanks 👍
    1978 GS750C

  2. #2
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    Jun 2010
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    Kenya
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    Quote Originally Posted by Mary Hinge View Post
    I've recently run the bike up a few times after a rebuild using a remote fuel tank to visibly check to leaks & balance the carbs etc., whilst doing so I had the petcock vacuum pipe on carb #3 plugged with a bolt. When I removed the bolt ready to connect to the petcock once the tank had been refitted I noticed it seemed to be moist with fuel, not running/dripping out but visible, in the end of the pipe. Is this normal & nothing to worry about or something that needs checking out ? Thanks 
    Visable as a dampness in the tube you mean? That is supposed to be a vacuume pipe so shouldn't be wet at all... But doesn't sound like anything to worry about, are the float levels all ok?


    Don't say can't, as anything is possible with time and effort, but, if you don't have time things get tougher and require more effort.

  3. #3
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    You sure it's fuel ? Could just be condensation from running.

    Mad
    83 GS750E
    2006 ZX14
    2004 KTM 450 EXC
    2001 Yamaha Big Bear

  4. #4
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    Aug 2010
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    Sebago,Maine
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    Me, Id suck on the petcock vacuum line and see if fuel follows.....petcock diaphragm could be failing
    1981 gs650L

    "We are all born ignorant, but you have to work hard to stay stupid" Ben Franklin

  5. #5
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    Oct 2020
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    Appreciate your thoughts, just to be clear the pipe wasn't connected to the petcock and the was a small amount of fuel in the end when I unblocked it after running the engine up for while using a remote tank. I just can't think how or why it'd be there when the vacuum is pulsing/pulling (I've checked it) in the opposite direction, seemed to run fine, strange huh 🤷*@%^$♂️
    1978 GS750C

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