Original vented gas cap

[GaryL]

It has taken me a while to get my DZ to idle correctly. Yesterday I got some gas and the tank was pressurized. Is a vented gas cap supposed to hold any pressure? If it holds pressure could that affect how the car runs?

[JohnZ]

Yes, the "vented" cap has a pressure/vacuum valve in it, and if the tank hasn't reached the threshold for the valve, it will "hiss" when you remove the cap to refuel. 

[william1]

http://www.camaros.org/forum/index.php?topic=239.0

 vented gas cap, johnz how much pressure are we talking about, i have looked and looked but can't put my finger on it, i think but not sure,, i'm having the same problem, as soon as i bleed off the tank it accelerates fine, the tank was replaced before i got the car so i have no idea if it might be a issue with that,, was just wonderin,,, have a new cap coming....

[JohnZ]

http://www.camaros.org/forum/index.php?topic=239.0

 vented gas cap, johnz how much pressure are we talking about, i have looked and looked but can't put my finger on it, i think but not sure,, i'm having the same problem, as soon as i bleed off the tank it accelerates fine, the tank was replaced before i got the car so i have no idea if it might be a issue with that,, was just wonderin,,, have a new cap coming....

I don't have the specs for the valve in the cap, but my original worked fine until it started leaking, and I replaced it with a reproduction about six years ago, and that works fine too.

[sixt9x33rs]

My cap seems to hold a lot of pressure. When I take it off just seems to pop to hard. I dont recall having this issue with the original tank.

John Z would a tank change have anything to do with the pressure at the cap?

Thanks

[JohnZ]

My cap seems to hold a lot of pressure. When I take it off just seems to pop to hard. I dont recall having this issue with the original tank.

John Z would a tank change have anything to do with the pressure at the cap?

Thanks

Nope, the tank change wouldn't affect it - but a cap change might.

[jdv69z]

Yes, the "vented" cap has a pressure/vacuum valve in it, and if the tank hasn't reached the threshold for the valve, it will "hiss" when you remove the cap to refuel. 

My cap's original, and works  just as John describes when I refuel

Jimmy V.

[sixt9x33rs]

I have not changed the cap. I will check again to see if I have the same issue.