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fuel leaking out of petrol cap?

Discussion in 'Bay Tech Clinic' started by Jehd, Jun 2, 2007.

  1. Jehd

    Jehd New Member

    Messages:
    192
    Location:
    Brisbane West Side
    hey guys.

    Fuel seems to seep out of the petrol cap area all the time (see pic). I seem to always be cleaning the mess off. I never overfill or let it get to the top, so i dont know how this is happening.

    any ideas?
     

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  2. BrianK

    BrianK Well-Known Member

    Messages:
    8,043
    Location:
    Port Kennedy WA
    yep i have one of those crappy plastic caps that does the same, or should i say did. but it was only when i hung into left hand turn. get your self some cork gasket material and make up some gaskets to fit in there. mine only just bearly does it now. i could not find the cork material at the time so i used some pieces of lino. i then found a shop that sell all the cork material you could think of. but the lino is still there.

    cheers brian
     
  3. Saggas

    Saggas New Member

    Messages:
    1,071
    Location:
    Canberra
    the petrol cap isn't sealing?.
    when you remove the petrol cap do you get a 'shh' of pressure?
     
  4. Jehd

    Jehd New Member

    Messages:
    192
    Location:
    Brisbane West Side
    i have inspected the seal before, and it looked in good nick. I will check for the depressurising noise next time i fill up.

    I thought it did it, but now i am not sure.

    Will keep posted
     
  5. Jehd

    Jehd New Member

    Messages:
    192
    Location:
    Brisbane West Side
    turning corners does explain it, i love my fat tyres :)
     
  6. Blue76Bay

    Blue76Bay New Member

    Messages:
    26
    Location:
    Western Sydney NSW
    I think the problem may be that your petrol tank is not venting properly. Therefore there is a build up of vapour in the tank. I have had this problem. It didn't leak when the tank was full but when it got below about half a tank, petrol would leak out of from under the petrol cap.

    From the fuel tank there are venting tubes that run up the inside of the fresh air vents on either side of the bus. These tubes cool any fuel vapour and forms a liquid which then runs down the tubes back into the tank. Any vapour that doesn't turn into liquid flows over the top of the bend in the tube in the fresh air vents and back down to the engine bay. In the engine bay the tubes from each air vent connect at a rubber T-piece in the middle at the top of the engine bay. Depending on the year of your bus, a rubber/pastic hose from the T-piece then connects to the Carbon Cannister or to the top of the Air Filter. When the car is running a vacuum is present in the Carbon Canister/ Air Filter and this draws the vapour off the fuel tank which flows via the venting tubes. This vapour goes back into the carby to be burnt off. My theory is that if there is no vacuum, the vapor doesn't flow in the tubes properly. Vapour in the tubes eventually turns into liquid after the bend in the fresh air vents and get caught in the bends in the engine bay. Fuel liquid in these bends in the engine bay eventually block off any vapour flow. This therefore causes the fuel tank to be unvented while driving and eventually the vapours build up in the tank causing it to leak out of the petrol cap.

    What I found on my van was the T-piece in the engine bay had perished. I replaced it but the problem still occured. I checked the Carbon Cannister and found that there wasn't an airtight seal around the join where the cannister can be pulled apart. I got some cloth tape and wrapped it around the join which sealed it well. The important thing is to make sure there is vacuum otherwise the vapors won't get vented from the tank. I think taking the rubber/plastic hose from the T-piece to the Air Filter would work better as the vacuum would be greater. You may have to cut a small hole in the Air Filter and rig up a small metal tube through gland nut.
     
  7. Jehd

    Jehd New Member

    Messages:
    192
    Location:
    Brisbane West Side
    well you may also be right too because i think that T piece is broken. I will check that too!
     

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