Gas tank pressure question

[neoworm]

Lately I occasionally seem to have an abnormal amount of pressure buildup in my tank. It started this summer when it was hot and I was at altitude and I didn't worry about it too much. It's getting more frequent and I'm back at sea level again so now I'm wondering.

I'll park the truck in the garage after driving for awhile and I can hear pressure escaping from around the filler. Once when I removed the cap, pressure was escaping at an unbelievable rate and for a very long time. Lot's of hissing and gurgling. It was wierd.

No check engine lights and seems to be running normally other than my mpg has gone way south but I chalked that up to my new SLEE rear bumper. It's an 03.

Any ideas anyone?

 

[spressomon]

A number of threads about this ranging from: Time to replace the charcoal canister (damn...I wish it was as easy and cheap a fix as the 80-guys figured out!), to plugged vapor lines, to ethanol, that is in most of our fuel these days, being a contributing factor...

Mine does it...so I assume its because I have 2x the onboard fuel with my aux tank and therefore overwhelming the EVAC system/charcoal. Its worse on hot days climbing around in higher elevations.

 

[rusty_tlc]

Mine does it in similar situations too, so the extra fuel capacity probably isn't a factor.