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FUEL TANK VENTING

Discussion in 'The Garage' started by jackedjimmy, Jul 10, 2002.

  1. jackedjimmy

    jackedjimmy 1/2 ton status

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    On my 81 jimmy I have removed all of the factory gas ad brake lines and am going to replace them with new ones. The truck orrininally had a 305 in it and when i got it, it had a fried 350 in it. Any way, I wanted to know what I should do with all ofthe remaining leads that come out of the 31gallon tank.

    There are atleast three venting leads that come out of the tank and I was wondering if I should just run rubber lines up into the fenders and use a diff breather to cap em off.

    The reason I'm doing this is becaus I'm switching to an electric fuel pump and a fuel filter in the frame rail ad i don't see the need for the extra lines.
     
  2. outlaw612

    outlaw612 1/2 ton status

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    I would just run 1 vent tube and block off the other 2. The last one I did only had 3 lines coming from the tank. 1 vent, 1 fuel supply line and 1 fuel return line.
     
  3. Greg72

    Greg72 "Might As Well..." Staff Member Super Moderator

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    I'd like to vent about my fuel tank too....it's only 20 gallons, and I get about 7 MPG! I have to fill it a lot!

    /forums/images/icons/grin.gif /forums/images/icons/grin.gif /forums/images/icons/grin.gif /forums/images/icons/grin.gif /forums/images/icons/grin.gif /forums/images/icons/grin.gif /forums/images/icons/grin.gif /forums/images/icons/grin.gif

    .....the coffee's kickin' in!
     
  4. BurbinOR

    BurbinOR 3/4 ton status

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    Doublecheck what those three lines really are........if memory serves me, ONE is supply to the motor, ONE is return line from the motor, and ONE and ONE only is the vent that runs up to the engine compartment to the charcoal canister. That return line is kinda important - helps vapor lock from happening. /forums/images/icons/tongue.gif
     
  5. jackedjimmy

    jackedjimmy 1/2 ton status

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    That sounds good but i am not going to run a charclo canister because of hte new electric pump. so what should i do about the return line.

    I don't think that there is a lot of gas actually coming back, it's probably just vapor right?
     
  6. TopOff

    TopOff 1/2 ton status

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    For my TBI setup I ran a 5/16 return line (as called for), I got some steel tube in four or six foot sections from local autoparts store. Then I T'd this into the fuel filler tube. All is well now for the last four years!

    This way I was able to keep my vent line, charcoal line, and feed line.

    Good luck with yours!
     
  7. chulisohombre

    chulisohombre 1/2 ton status

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    my 72 has about i think 5 lines coming off of it and plus the fill tube.i was wandering if i could block off the ones going up into the cab of the truck.theres 3 of them or do they go up in to the filler neck?mine are all dryrotted and can only fill truck 3/4 of the way.
     
  8. 84K5BD

    84K5BD 1/2 ton status

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    when i converted over to the electric pump , ran 1 line to the pump, then to regulator, capped off return line and ran
    vent line up to feul filler door to keep vent up high for deep water crossings and mud worked great
     

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