Last week on the trail in Moab I was getting crazy pressure build up in my gas tank to the point it would occasionally blow gas out of the fill cap. It makes no sense because the two vent lines from the tank are unobstructed, the roll over valve is open and unobstructed and the vent line to the charcoal canister is unobstructed. The canister checks out with no obstruction and the ported vacuum line from the throttle body applies vacuum as soon as the throttle plates open. I’m suspecting the 42 year old roll over valve is acting up and I now have a newer replacement on order. Am I missing something here?