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Thread: gas pouring out of the carb vents

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    Senior Member 2billydavies's Avatar
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    gas pouring out of the carb vents

    hi everyone.... me again. shocking!
    can anyone tell me why on occasion when my TR3a is idling gas just pours out of the carb vent pipe on top? it did it again today.... just pouring out of the left carb. no clue why. I undid the bolt on the top of the float bowl, took off the lid... then bolted it back on and it stopped. before I did my engine rebuild the right carb did it. same thing g.... i undid the lid, put it back on, and it stopped. the vent pipes on my carbs do not lead to anywhere.... just a long skinny pipe sticking out. I ts driving me crazy!
    thanks.... again... for the great help!

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    Yoda Geo Hahn's Avatar
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    Re: gas pouring out of the carb vents

    Sounds like a stuck valve in there. Sometimes you can clean them and work them a bit and they are fine, sometimes it is best to replace.

    There are several types of valves - some have a needle and seat and some use a small metal ball (like a check valve).

    For both types you usually remove the pin that hold the arm, then undo the hex that is the body of the valve.

    If an engine sits for awhile they are prone to sticking so if that is the case possibly just working them a bit will free them up.

    Could also be a sunk float -- to check you can remove the float and shake it listening for gas inside.

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    Senior Member 2billydavies's Avatar
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    Re: gas pouring out of the carb vents

    awesome. I thought maybe something was "stuck." the car sat for 6 months during the rebuild. im going to check everything you suggested. thanks again... this forum has been a total lifesaver!

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    Yoda Geo Hahn's Avatar
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    Re: gas pouring out of the carb vents

    Even if it is a valve - check the float anyway while you have it open. You can bend a length of stiff wire (even a big paper clip may work) into a tall 'L' and slip it down alongside the float to hook it underneath and lift it out. If there is gas inside it, it is probably best to simply replace it rather than try to repair.

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    Great Pumpkin TR3driver's Avatar
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    Re: gas pouring out of the carb vents

    My opinion, if you find the valves with the metal ball, chuck them and use the Viton tipped needle valves. The valves with the balls (aka Grose Jets) are commonly sold as improvements, but I have seen them cause exactly the problem you describe more than once.

    Also, take a look at the short sections of soft line that connect the carbs to the line from the fuel pump & the bridge piece between the carbs. They can deteriorate internally and shed bits into the fuel, which can block the float valve open and cause overflow. I consider it worthwhile maintenance to just replace them every 10 years or so.
    Randall
    56 TR3 TS13571L once and future daily driver
    71 Stag LE1473L waiting engine rebuild
    71-72-73 Stag LE2013LBW waiting OD gearbox rebuild

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    Yoda
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    Re: gas pouring out of the carb vents

    If not what has been said, perhaps an electric fuel pump with too much pressure.

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