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Thread: Fuel Tank Venting

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    Fuel Tank Venting

    I know this has been discussed before but I wanted to share what my research has found and, also, ask for possible solutions. As noted in the past, some of us leave a trail of fuel when making a left hand turn with a full or nearly full fuel tank. Fuel goes out the vent/overflow tube on the passenger's side of the tank. While researching I checked two original tanks I have and the hole at the bottom of vent plug where the banjo bolt goes was on the passenger's side of the plug. On the tank that drains fuel through the vent tube, that hole is on the driver's side of the vent plug. Consequently, when you make a left hand turn, fuel swings to the passenger's side and out the vent tube. Were I able to use my original tank there wouldn't be a hole there for fuel to go out. I was told the supplier of the tank said this sometimes happened. So I called a vendor who happened to have four tanks in stock and was kind enough to check them. He found the holes were all over the place. Appeared to be just randomly place. No two in the same location but none of the four directly in line with the fuel when it would swing to the right. On my original tanks I don't know if Triumph was more meticulous and put them directly away from a majority of the fuel or I just got lucky with those tanks. Anyway, finally my question. It seems the only way to stop fuel from going out the vent tube would be to block it. I know other's have done this so what is the best way?

  2. #2
    Yoda CJD's Avatar
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    Re: Fuel Tank Venting

    Can you post a pic of the hole you’re talking about?
    John

    1955 TR2

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    Re: Fuel Tank Venting

    John the hole I'm talking about is inside the threaded fitting the banjo bolt goes into so I've found it impossible to take a picture of it. I tried once with no luck. I'll try again in the morning with a bright light shining into it and maybe it will work. Sorry. If you have a spare tank look in the fitting where you would place the banjo bolt.

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    Re: Fuel Tank Venting

    John I was able to get a pic of the hole. The hole is on the passenger side of the tank.DSCN1554.jpg

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    Yoda CJD's Avatar
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    Re: Fuel Tank Venting

    Interesting. That entire fitting is brazed into the tank, so it could easily be rotated. And you're thinking that the hole should be towards the outside of the tank?
    John

    1955 TR2

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    Re: Fuel Tank Venting

    If you have a repro cap like the one I got from TRF for post 60k tank it may have a vent hole in the cap.
    I would seal the tank vent,and drill small hole in cap to venti.I believe Randall posted pics of this if you search.
    Tom

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    Re: Fuel Tank Venting

    John you're right, the fitting is brazed into the tank and the aftermarket suppliers aren't paying attention to how it goes in. On the two original tanks I have, that hole is to the outside thus leaving only about 3 inches of fuel that can slosh around and it wouldn't overflow the vent tube. That's what is pictured. With the aftermarket tank I now have, the hole is to the inside and even with a tank 3/4 full I get fuel out of the vent tube in a left hand turn. At any rate, my fuel cap is vented so I will remove the vent tube and plug the hole. For those interested it takes a 1/2 - 20 bolt 3/4 inches long or less. Just wanted to let all know so they could be on the lookout for this potential problem.

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    Jedi Warrior PatGalvin's Avatar
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    Re: Fuel Tank Venting

    Quote Originally Posted by TFB View Post
    If you have a repro cap like the one I got from TRF for post 60k tank it may have a vent hole in the cap.
    I would seal the tank vent,and drill small hole in cap to venti.I believe Randall posted pics of this if you search.
    Tom
    Hi All - Back to the forum after a little time away. I recently replaced my pitted fuel cap (TR3A) with a new one from Moss and it was drilled with vent hole. Too lazy to pull apart my interior and expose the fuel tank banjo connection to plug it - so, I went on Amazon and bought a brass fitting (5/16 compression by 1/4 inch MPT) and installed it on the end of the vent pipe, with an NPT cap, down near the differential. Next time I take out the interior (rear seat and capping), I'll remove the vent pipe all together and plug with the half inch diameter cap screw. I used to lay down way too much gasoline on the pavement on those left turns. People would honk and complain.

    https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

    71bSzkuEjHL._AC_UL115_.jpg
    Pat
    Pat
    59 TR3A TS38096 L
    1968 TR250 CD6021LO

  9. #9
    Obi Wan
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    Re: Fuel Tank Venting

    Interesting

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