Vapor-Liquid Separator

Discussion in 'Fuel and Air Systems' started by Lil Demon, Jun 7, 2018.

  1. Lil Demon

    Lil Demon Well-Known Member

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    Anyone try using the original vapor-liquid separator? From looking at the diagram of how it works, looks like the best way to vent my new efi setup. I figure connect the three vapor hoses to my top tank vent line, then connect the vent-liquid return line to my fuel pump vent inlet to return any possible liquid introduced into the separator. Anyone try this?

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  2. 67Dart273

    67Dart273 Well-Known Member

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    No. The line which goes up front, and originally connected to the carbon can system up there IS THE VENT and MUST BE open to the atmosphere

    ...........at least if I understand what you are trying to do. If the tank has a dedicated vent line you need to use that for a VENT and it must go up high to prevent siphoning. This is why the 69/ earlier system with the vent "teed" into the filler tube worked so well. It was almost impossible to create a siphon situation with that.

    Only situation I can imagine is that EG you filled it VERY full with cool gas, then parked it with the filler on the downhill side of a very steep hill.

    Even then all they would do is siphon down enough to create a space in the filler neck and then "break" the siphon.
     
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    • Lil Demon

      Lil Demon Well-Known Member

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      Correct the highest point is the best vent. That is why I am thinking of using the tank vent as the vent and plumbing it to the Vapor/Liquid separator, then use the fuel pump vent line as a return line from the separator. That would contain any possible liquid that may find it's way into the separator.
       
    • 67Dart273

      67Dart273 Well-Known Member

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      Ok but how are you actually going to vent it? Some of the lines in the separator go to the bottom, some don't. So you could get a situation that might cause a siphon, and you might get a situation that would allow fuel to build up in the separator and not drain. In other words you must be careful what you hook to what.