Both fuel tank vents needed? Hmmm....

Fuel and Air Systems

  1. Sonny

    Sonny FBBO Gold Member FBBO Gold Member

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    13C9D48C-8117-4531-9816-BF18278FC585.jpeg I am installing a fuel filter that has the 1/4” vapor breaker nipple that runs to the fuel tank. I am also replacing the 2 old fuel tank vent lines and it got me thinking?? Are both those vents needed? See where I’m headed with this?

    I lieu of dropping the tank and replacing my “recently” new single port fuel sender with a dual port sender/return, can I use one of the vent lines (the short one) instead? I realize it’s no longer a vent if I do. Could always add a vented cap for redundancy?

    Yes I’m being lazy.
     
  2. 69Bee

    69Bee FBBO Gold Member FBBO Gold Member

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    No. If the factory had intended for it to work that way, then they would have done it. The two vents serve two functions, and should remain. The short tube looks to be an overfill relief, and the longer tube for a vent. The length is specific so that fluid doesn't escape, and I am willing to assume the inner tube is long and goes to the rear (fill tube side) of the tank. Do it properly, and get the return tube pickup...
     
    • Thanks! Thanks! x 1
    • Sonny

      Sonny FBBO Gold Member FBBO Gold Member

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      75D3AEC7-A50B-4BC6-9FBB-ED44980B1DBE.jpeg
      I “could” add a T into the bottom of the long vent line at the tank nipple and still have both vents. That’s all the vapor separator is -another vent technically to relieve pressure. It’s not a return line.
       
    • Sonny

      Sonny FBBO Gold Member FBBO Gold Member

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      I don’t disagree with you, but the physics behind it would work (see my sketch below). I think the tank vent nipples are smaller than the 1/4” vapor line so it doesn’t match up anyway.
       
    • steve340

      steve340 Well-Known Member

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      The vapour separator is the pressure side of the fuel pump so sorry it will have raw fuel in that line returning to the tank. I would connect it to the sender return tube the way it was designed.
      The reason you do not have a vented cap is fuel will come out when you accelerate or the fuel sloshes against the cap.
      69Bee is right stick to stock design and it will probably work OK.
      It is easy to get the sender unit out no need to drop the tank.
       
    • Sonny

      Sonny FBBO Gold Member FBBO Gold Member

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      Looks like the sender is close to the trunk floor and at an angle. I’ll try and remove it with the tank in. Didn’t think that was possible since the sender face is at an angle towards the floor.
       
    • Bill Monk

      Bill Monk FBBO Gold Member FBBO Gold Member

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      I agree with the other comments, it just won't work. I used a long wooden dowel and tapped the lock ring out. I have a removal tool but I never had much luck with it with the tank installed
       
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