According to an article on aeromotives site it says that Now my question is, is a fuel tank suppose to be pressurized via the cap sealing, or non presurized via the cap venting? Reason i ask is i lost the stock fuel cap and replaced it with a locking one, since then when you take the cap off it releases a decent amount of pressure.

Anyone have some thoughts?

 

Not too sure, I know mine is always pressurized when I take my stock cap off.

 

Mine releases a decent amount of pressure as well. It's a stock cap however.

I've noticed, the longer I wait to refuel the more pressure releases.

You got me...

 

I thought they held a vacuum, that is why they test your gas cap during an inspection with a vacuum pump. My cap always sounds like it is sucking air into the tank when the cap is taken off, not the other way around.

 

Curious that they would say that. The cap is a non-vented type. They can't be talking about our cars. Ever notice that little round thing with a hose on it that is attached to the left rear brake hose bracket? That is the pressure/vacuum relief valve (vent).