Results 1 to 9 of 9

Thread: Does your fuel tank build pressure when hot and low on fuel ?

  1. #1
    Join Date
    Jan 2004
    Location
    Nashville, TN
    Posts
    982

    Default Does your fuel tank build pressure when hot and low on fuel ?

    Filled up today. Car has always vented when I take the gas cap off. Moreso when its hot out and the fuel is low- Is this normal ? Have noticed a fuel smell in the garage - not sure if its the BMW or not.
    Derek A.
    90 535i 5 Speed - Style 5 17"

  2. #2
    Join Date
    Oct 2005
    Posts
    518

    Default

    Mine does this almost every time. Most older cars seem to build up some pressure and I think it may be due to the less advanced fume control system that most of them had.

  3. #3
    Join Date
    Jan 2004
    Location
    Nashville, TN
    Posts
    982

    Default

    I got home and it looked like fuel was dripping from the left hand side of the tank... ideas ?
    Derek A.
    90 535i 5 Speed - Style 5 17"

  4. #4
    Join Date
    May 2004
    Location
    Japan
    Posts
    9,139

    Default

    I have no magic eyes, why do you not have a look under the car.
    Fuel tank
    http://www.realoem.com/bmw/showparts...87&hg=16&fg=05
    Maybe something wrong with ventilation or return line system
    http://www.realoem.com/bmw/showparts...78&hg=16&fg=10
    check these hoses and connections. In case of my car I have to remove the rear wheel right side, then the plastic insert under that fender, then you see the expansion tank and the hoses. I replaced them all
    http://www.realoem.com/bmw/showparts...03&hg=16&fg=10

  5. #5
    Join Date
    Dec 2003
    Location
    Wellington,New Zealand
    Posts
    3,868

    Default

    i frequently run my car from full right to empty ie light may be on fr 40 or 50 km.I have never noticed any "venting" but i am not 100 per cent sure we have the same fume control system at all.
    Gone but not forgotten

  6. #6
    Join Date
    Feb 2006
    Location
    Oldham, England
    Posts
    3,078

    Default

    Quote Originally Posted by Derek A.
    Filled up today. Car has always vented when I take the gas cap off. Moreso when its hot out and the fuel is low- Is this normal ? Have noticed a fuel smell in the garage - not sure if its the BMW or not.
    Think what you hear is more likely air rushing in than out-caused by a slight vacuum in the tank. Makes sense if you start off with the air above, say 3/4 tank and then pump out 1/2 tank you will be left with less air pressure inside than out. If its serious your tank would crease inwards. Remember petrol caps used to have vents to prevent this but these days the systems must be much more clever

  7. #7
    Join Date
    Jul 2004
    Location
    Vancleave, MS
    Posts
    629

    Default oh yes...big time.

    ...in the summer...

    get in after work, cars in the 100s F scale...hot...

    got a quarter tank... can go a few days on that....

    whoops.... tank cools w/air from driving... next thing I know I'm on vapor.

    crap..it's been about 400 miles... guess i better get some gas.
    1993 / 525ia / M50TU / EAT / Sachs / Infiniti Kappa & Basslink / super clean / Style 5s wearing Pilots / Mobil 1 everywhere / long road ahead

  8. #8
    Join Date
    Aug 2006
    Location
    Houston
    Posts
    241

    Default

    I get that smell mainly when over half a tank. its rather anoyying dont know what is causing it just yet because i havnt been able to reach the res tank to check it

  9. #9
    Join Date
    Jan 2004
    Location
    Nashville, TN
    Posts
    982

    Default

    What is the pain in the ass factor in getting that wheel well out?

    Car is now dripping fuel from the muffler area. Going to have to park it until I can get a look.
    Derek A.
    90 535i 5 Speed - Style 5 17"

Similar Threads

  1. Replies: 9
    Last Post: 02-14-2008, 01:36 AM
  2. HELP! can't get fuel pressure regulator out of fuel rail....
    By ryan roopnarine in forum 5 Series BMW
    Replies: 2
    Last Post: 01-21-2007, 09:26 PM
  3. Replies: 4
    Last Post: 01-13-2007, 01:47 AM

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •