Excessive Gas Tank Pressure when it's hot outside

[2erobrd]

Well, Happy 4th of July guys !!!!

so in-between chores today I disconnected the "vent" tube from the gas tank and blew it out with about 80lbs of compressed air.

And the result was as I figured, nothing came out other than 80lbs of air pressure. I also inspected the vent tube as it's not s simple as you would think, it goes up from the tank to the top edge of the trunk, then travels all the way under the inside of the right her fender. Then it makes a crazy hairpin turn back towards the rear of the vehicle and down right behind the bumper.

All in all, the tube is a factory part, not kinked, not bent, not rusted and certainly not obstructed by any means.

another observation I made today is that even though it was only about 85 degrees today it was no where near as hot as it had been the last few days. Anyhow, I pulled the car in reverse up the driveway instead of down the driveway in hopes of seeing if it would leak today after I blew out the tube. we got up to 91 today and nothing happened today, no excessive pressure and no leak out of the vent tube.........

any other suggestions ?

[Luva65wagon]

There's really no way for the tank to have bloated if the vent tube was in-fact clear. Maybe 80 PSI dislodged something, or shifted it, but it is still inside the tube and now is finally letting air pass by. Hard to say, but you can't blow up a balloon with a hole in it. I'd pull that tube loose and chase a wire though it, if possible, to see if a lump of something doesn't come out.

Agree with Phil regarding the internally located cap. Some cars, like my 65 wagon and Gene's 65 Ranchero, have no vent tubes and used a vented cap. I think most early cars did. My Ranchero, though, did have a vent tube just like you describe. Gene's doesn't have a vented cap now and he lamented a week ago about hearing a big woosh when he released the cap. No surprise. He's thinking of adding a vent tube because he's relocated his filler into the bed under his bed cap.

The design of the vent tube is such that fuel should never get pushed up that far. You would have to have a full tank to the cap level and tilt the car on its side. But if you had pressure like you said, it might have occasionally purged the pressure through that tube with enough velocity to where some raw fuel came along with.

What happened happened, clearly, but I would verify all is clear and go back to normal driving to see if you fixed/changed anything. Should be quickly obvious and you'll never know until you try.

Too bad it is gas fumes you are having to experiment with, though...

[ew1usnr]

I disconnected the "vent" tube from the gas tank and blew it out with about 80lbs of compressed air. And the result was as I figured, nothing came out other than 80lbs of air pressure.

Maybe the blockage is upstream of where you blew air through. Look in the nipple where the hose clamps onto the gas tank.