Gas tank issue

Discussion in 'Other' started by priariecanary, May 14, 2013.

  1. priariecanary

    priariecanary Stacey

    I drove home from work this afternoon in my 67 GS. it was the first day when the temps were over 90. I stopped after 30 minutes of driving an notice a small puddle under the rear bumper. The puddle turned out to be gas leaking out from what appears to be a vent tube the rear driver's side of the fuel tank. the line is pointed up and tucked up near the top of the inside of the bumper. The end that is not connected to the fuel tank appears to be open to the atmosphere. The previous owner replaced the fuel tank and so I am not sure if everything was done properly but I am guessing something is up since the fuel is supposed to stay on the inside of the tank. Any clues as to what is going on and how to correct it?

  2. lemmy-67

    lemmy-67 Platinum Level Contributor

    I don't know how it is on the GS, but on the 67 Riviera, that vent pipe goes to a hose which connects to a loop of metal which goes into the trunk compartment. The loop allows the fuel vapors from the tank to condense, and then drain back into the tank. Look for a fitting above where the tank is mounted, and connect the vent pipe on the tank to it with a new hose. You may even still have the old hose hanging there from under the trunk.
  3. Couch

    Couch '67 GS400 Guy

    No metal tubes on the A-body GS's, there should be two hoses there under the bumper from the tank (one is 1/2" the other 3/8"? if I recall right), and they both go up and end under the body lip and just vent to the outside air. I have my original tank and have never had an issue with venting liquid fuel thru those hoses? And I have been in some warm areas (car was original to Fresno, CA. area). Now just what those tubes do inside the tank :Do No:, I have had my tank out but never really took a look at what those two pipes do? Mike
  4. priariecanary

    priariecanary Stacey

    Thanks for the info. I looked under there this morning and can confirm there aren't any metal tubes.

    Fuel was burping out of the rubber tube on the driver's side, I didn't think to look for another tube. Maybe the other tube was plugged causing the left tube to leak gas. I need to install some of those rubber anti-squeak pads between the tank straps and the tank anyway. I will see what is going on when I do that.
  5. lemmy-67

    lemmy-67 Platinum Level Contributor

    Well, if there's no condenser in the trunk, there should be something on that vent pipe to allow the air to escape and the fuel vapors to condense and drain back into the tank. It's definitely not part of the factory design to have raw fuel pouring on the ground in hot weather. I can check my 67 chassis service manual files, maybe there's some info there for the 67 A-body fuel tank setup.
  6. gsman

    gsman '67 GS 400

    I'm had EXACTLY the same problem tonight only my vent tube is not attached to anything but gas is coming out when I accelerate hard. Does this definitely have to be routed back to the tank or can I simply plug it up?


  7. CJay

    CJay Supercar owner Staff Member

    According to the service manual that Im sure you guys have right?, there is a drawing on how the vent hoses are supposed to run.

  8. flynbuick

    flynbuick Guest

    No, you cannot plug the vent tubes. If you do, fuel; stop flowing to your carb.
    Yes, a 70 tank can purge a little fuel in the summer. Make sure both rubber hoses are clamped to the suge tube. The surge tube is held against a vertical metal surface by a clamp that is bullt into the car. Try to not top the fuel tamk off when it is so hot and avoid parking it hills.
  9. gsman

    gsman '67 GS 400

    I have the service manual that I got online from Is there anywhere the tubes are supposed to be routed or do they simply stick up in the air like the picture?


  10. Gary Bohannon

    Gary Bohannon Well-Known Member

    You have one of two vent tubes plugged internally. The other vent will close eventually. Then fuel will be trapped under pressure and vacuum conditions. As of now, this is happening to one tube depending on angle you car sits and level of fuel.
    I had the same problem.
    Vents... One tube goes to a front corner and the other to the opposite rear corner. You cannot clean out these tubes when they rust shut.
    You need a Spectra GM37G tank with 2 internal vents and filler tube included. It will be listed as 1966-67 Olds Cutlass only. It is an exact identical 67 Buick GS tank. Don't expect Spectra to list it correctly. I wasted phone calls trying to tell them.
    Tank is absolutely perfect copy and fit.

    ---------- Post added at 10:17 PM ---------- Previous post was at 10:07 PM ----------

    By the way... The external RUBBER tubes simply plug into the tips of the long steel vent tubes that are made inside the tank.
    The RUBBER tubes are supported by a thin metal strap, between the trunk and bumper, that keeps them pointing upward higher than fuel level and sheltered from water (rain or car wash).

    ---------- Post added at 10:26 PM ---------- Previous post was at 10:17 PM ----------

    Look again for two tubes close together and mabe one rubber hose missing.
    If it is a single vent tank, it is not original for a GS and I don't have a clue to help.
  11. CJay

    CJay Supercar owner Staff Member

    I guess the OP could try blowing some air into the vents to see if they're clogged. Best case as you mentioned, is if one of the two hoses is missing

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