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high vacuum building up in my fuel tank

Discussion in 'Diesel Tech and 24 volts Systems' started by mike, Dec 11, 2008.

  1. mike

    mike 82bj42 1st project

    Messages:
    1,681
    Location:
    Toronto,Canada
    What can be the cause of high vacuum building up in my 87hj60 fuel tank? I can bearly remove the fuel cap when I go for refueling.
    Thx Inadvance
  2. roscoFJ73

    roscoFJ73 New Member

    Messages:
    11,864
    Location:
    Perth Western Australia
    Go the right tank cap on?
  3. mike

    mike 82bj42 1st project

    Messages:
    1,681
    Location:
    Toronto,Canada
    I'm not sure. This cap came with the truck. I will purchase a new one from Toyota to see if it makes a difference. Thx
  4. seapotato

    seapotato New Member

    Messages:
    3,484
    Location:
    Lacus Oblivionis
    mine does the same( 87 bj70, but similar deal)


    I know the reason mine does it, there's a pile of vent lines that come off the tank, and some of them were rotted off so I plugged them so crap didn't get into the tank. Ever since, big vaccuum, gas cap is a bitch to get off, but doesn't seem to affect the way the truck runs, so I can live with it.

    So, I'd have a look at the other lines that come off your tank.
  5. mike

    mike 82bj42 1st project

    Messages:
    1,681
    Location:
    Toronto,Canada
    Good idea, I'll have a look at all the metal lines that come off the fuel vapour separator. Thx
  6. mike

    mike 82bj42 1st project

    Messages:
    1,681
    Location:
    Toronto,Canada
    I found the problem-- your right. One of the steel line's ends was pluged up. I unpluged it and the tank's pressure is normal again. Thx
  7. Icefire

    Icefire Regular Member

    Messages:
    162
    Location:
    London, Ontario, Canada
    Another good solution to that problem is to drill a small hole in the fuel cap.
  8. jzilla

    jzilla New Member

    I just replaced my tank and 2 of the lines on the truck were rotted so I plugged the hoses as well.
    Looks like another one is leaking so I will have to plug that as well! Truck runs fine but could you not also run a hose up into the body somewhere? The gas cap idea sounds like it would be good to. So are the vent lines only so that the tank does not implode?
  9. mike

    mike 82bj42 1st project

    Messages:
    1,681
    Location:
    Toronto,Canada
    The imploding is a defineate reason for the one of the vent lines----the longer on that goes over the rear axel. My tank has normal pressure after unpluging that long vent line.
  10. jzilla

    jzilla New Member

    Are you talking about the steel line that does a loop and then goes under the body to the drivers side?
    Mine is just rusty so I cut it shorter several years ago. Never had a problem.
  11. mike

    mike 82bj42 1st project

    Messages:
    1,681
    Location:
    Toronto,Canada
    That's the one. I cut mine shorter also. Mines working fine now. Thx

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