hello sages- have solved a number of problems with my 80 volare wagon as a result of wise counsel from dan and other sages on this forum. very grateful. had postponed solving this one while i resolved other more pressing mechnical peccadillos. problem remains that when i remove the cap i get a substantial outgoing surge of air pressure. what i have done- tried a few caps which have the popoff pressure relief valve in them. no change. replaced the gas filter and gas hoses(all were deteriorated) at the tank, gas filter and under the front of the rf door. no change. checked the metal lines, rollover valve and canister at the front. all seem ok. it doesnt affect the running of the car.nor does running the car have any effect on the pressure accumulation. seems clear the pressure is coming from heating under the fla. sun .later at night when it is much cooler, there is little or now pressure release when i uncap the tank. now heres the rub. uncle moe and a chrysler dealership mechanic both tell me it is a non problem. all f bodies did that since it was a vapor closed system for emission rules. there is even a warning about it on the cap(ie, open slowly). moe said the popoff valve will release if pressure gets excessive anyway. dont remember having this problem on my long running 77 aspen wagon. should i fugedaboutit or do something? thanks tons. bob f

So what are you saying? Putting Beano in the tank cured your vapor pressure problems? If so, how much Beano? I could really use more info on your subject here, as I've been having problems with a A100..

not sure if beano would work, but it might. need to hear from a real specialist in gas problems. does anyone on this forum generate high gas pressure and has effectively cured it? months ago someone on the forum not only helped me with a clogged cat but actually forwarded a clear picture of one. wow never saw anything like that cat. my 80 f body has this gas line system that returns gas to the tank. fuel goes from tank to filter to pump then there is a line which returns fuel to the tank. all in the name of emissions. does your tank build up pressure which then blows out when you open the cap? what do you think i should do about it? regards paladin