After driving for 3 hours on the interstate, I stopped for gas. I had about 1/2 tank showing, but I wanted to drain the kidneys and top it off. When I cracked the gas cap, it started venting. I figured no big deal I've seen this before. So I waited a few seconds and then loosened the cap some more. It was still blowing and now it started spraying gas out along with the vapor. So, I tightened the cap back up some to where it stopped spraying gas and just let it vent. I'll bet it was something like 30 seconds before it quit venting. That just doesn't seem right. Makes me wonder what pressure I had in the gas tanks. Is there a pressure vent/relief for the gas tank system. Is it supposed to maintain pressuer by venting throught the charcoal canister system? What if this doesn't work? Is there a backup vent? I had visions of the tanks rupturing and unloading all their fuel on a hot exhaust system while driving down the highway.
I have checked the gas cap many times since then and have not seen it do this again.
Any help on this would be mucho appreciated