Gas tank blowing air out of cap

[Mattsauces]

i was driving up to the mountains the other day and it was 113 degrees outside. One i got up the mountin i turned off my explorer and i heard a noise like a motor comming from my gas tank. i open my gas cap and air is blowing back at me, it wasnt like a release of pressure, it was a steady stream of air blowing out. It seems like my fuel pump was still running but my ex was turned off, so i had to pull out the battery to turn it off. But even though the motor was off i was still getting pressure comming out of my gas tank. the pressure release slowed down then eventually stopped, but then if i opened it a minute later there would be another small relase of pressure that then died out. After a while there was no more pressure released. i reconnected my batter about a half hour later and everything was back to normal. What i dont understand is where this pressure was comming from.

 

[Tbars4]

...i'm not really sure how to answer your question completely but, gas expands with heat....i would be curious to have you get your codes read...your evap system should be taking care of this for you and your gas cap should not be blowing if it is in good shape...one of the reason's your gas cap is checked during smog check...that is also why on hot days when you fill up, you open your cap and a little pressure release might be noticed...also, driving up to the mountains with an elevation change you do have a air pressure change too...but again, your fuel evap system in proper working order should handle that just fine...just my thinking but your charcoal box might need changing but try and get your stored codes read first...

 

[MarkHuck]

i was driving up to the mountains the other day and it was 113 degrees outside. One i got up the mountin i turned off my explorer and i heard a noise like a motor comming from my gas tank. i open my gas cap and air is blowing back at me, it wasnt like a release of pressure, it was a steady stream of air blowing out. It seems like my fuel pump was still running but my ex was turned off, so i had to pull out the battery to turn it off. But even though the motor was off i was still getting pressure comming out of my gas tank. the pressure release slowed down then eventually stopped, but then if i opened it a minute later there would be another small relase of pressure that then died out. After a while there was no more pressure released. i reconnected my batter about a half hour later and everything was back to normal. What i dont understand is where this pressure was comming from.

My daughter's 96 releases pressure sometimes when the cap is removed. She filled the tank Friday, got a ride home from college Saturday, returned Sunday to find gas leaking. She took the cap off and gas shot out at her!! I need to figure out what is going on. Did you ever find a solution to your problem?
Thanks,
Mark