Gas cap should it be vented or non vented

[mytta49]

Want to put a new locking gas cap on and the listing at the auto parts store says for the 89, it comes in vented or non vented.
Any idea which cap the TTA uses ?
Thanks

 

[Swede2]

Its unvented if stock.

Daniel

 

[mytta49]

Thank you

 

[83ttypecooled]

Hi,
I pull my cap off, and lots of pressure. I guess that means unvented, Huh?

 

[3.8TransAM]

Some pressure is normal, a slight amount.

If u have a lot of pressure building up, either your canister purge isnt working properly, of your fuel tank vent valve is not letting in fresh air to dsiplace the gas used and causing the tnak to collpase on itself...

later
Jeremy