Gas Cap?

OK so in cars that I have had in the past when I undo the gas cap when the fuel is low it usually releases a lot of presure. In my 1999 1.8t Passat I don't get this release of presure. When I take the cap off nothing. Should I hear this presure release?

It's usually under vacuum on newer cars. It would also set a code if there was a leak in the system.

Could this be why I am getting that "Misfire due to low fuel" code that no one can seem to track down what is causing it?

See thread:
http://www.automotiveforums.com/vbulletin/showthread.php?t=339413

Are you sure it's releasing pressure when you remove the gas cap? It should be under vacuum. If it was pressure I would think it would do the opposite & always try to push fuel through the system, possibly flooding the engine.

No there is nothing when I take the gas cap off. No pressure or vacuum. Nothing at all...

If there were a problem with the tank, cap or EVAP system you would be getting a 440 or 450 series code. Have you tested the fuel pressure with a gauge?