Air Releasing After Opening Gas Cap On My Camry...

[Durrby]

What exactly does that mean. When I go to fill up and unscrew the gas cap a ton of air is released when I open it??? Anyone know? Is it normal?

[Erbe]

happens to me sometimes....didnt last night when i went to fill it up...i guess when you last shut it....air was caught inside the gas tank and was released.....

[zoni]

the fuel system is pressurized. when you open the tank cap, the pressure is equalized with the atmosphere, thats the rushing of air.

[D0UG]

vapor pressure:

It is the measure of how volatile a compound is; the lower the vapor pressure, the less volatile the compound. Think of it as the pressure that must be exerted to maintain a compound in the liquid phase. The more volatile the compound, the more pressure that is required. Vapor pressure and boiling point are thus inversely related: the lower the boiling point, the higher the vapor pressure.

[CamNub]

I started a thread about this topic once. Search for it.

[white90dx]

Durrby, how many cars have you driven in your life? All cars with EFI and emissions control do that if they are working correctly.

-Charlie

[Velocity]

I work along with The Rail & fuel Commission of Texas on a daily basis....I had to take a course on this type of stuff called "Vapor Recovery Stage II Training"...

Its called vapor recovery. Its kind of like what Zoni said but its actually pressurized fuel vapors that is released into the atmosphere that contaminates the air......Each and every fuel station has their pumps EPA certified (and TRC certified in Texas but depends on state) to capture the vapors every time you fuel up.......The vapors are then taken from your vehicle, and then stored in the stations underground tanks......Vapors are then loaded onto fuel tanker trucks at the same time it dumps its load to the station (kinda like a balacing act of vapors:fuel dump)...Vapors are then taken to the refinery and properly disposed or recycled........Also its not only EFI emmissions cars that do that its anything......Take for instance a fuel can. Fill it up, close it tight, leave it a day, then open it up, and "swoosh" its the same deal.......No EFI involved there.