Gas leaks out at high altitude?

[deepsleep]

Okay so the other day I took my box to 14k feet and when I got home, I noticed that there was gas leaking and had been dripping down the side of my car.

I did some searching on google but didn't come up with much except that maybe my gasoline is turning into vapor and my gas cap isnt holding it in. But at the same time, I remember reading a little while back about popping the gas cap open when at high altitudes because of the extreme pressure. Also, I did hear "popping" sounds when I was sitting in the car for a while at 14k feet. Not many pops, all together I heard only two but it sounded like the back area. And also, I think I heard the fuel pump (ive heard the whining sound in my old talon) high pitch whining sound..So whats going on and what should I do?

[Lincolnmania]

where at on the car was fuel dripping?

[Nathan in MI]

It sounds like there's something wrong with your tank vent. There's supposed to be a vent in there to help the pressure inside the tank stay the same as the pressure outside the tank. Otherwise, you run into problems like what you were experiencing. Could be the vent in the gas cap is plugged, could also be one of the hoses for the evaporative emissions system is plugged.

[deepsleep]

where at on the car was fuel dripping?

It was coming out from the gas cap area.

Is there a way to test the gas cap, tank vent or hoses for the evaporative emissions system?

[1987cp]

You could spend a lot of time diagnosing this, but it's easier to go spend $5 on a new vented gas cap.

[gadget73]

replace the gas cap, if that doesn't help, you can dig into the evap system. On your car I think its a vacuum controlled valve, labeled CANP on the vacuum hose diagram under the hood.

[deepsleep]

Okay, I'll get a new gas cap. How can I "dig" into the evap system?

Also, I just want to make sure having it closed shut isnt going to damage my fuel pump or anything right? I shouldnt pop the cap open before driving at high altitude?

[1987cp]

Just make sure your new cap is a vented cap, and you won't have trouble with pressure building up inside the tank even if the factory evaporative emissions system is completely inoperable.


"Digging into" the evaporative emissions system may involve tracing the entire route your fuel vapors take from the check valve on the top of the tank, along the hard line on the framerails, into the charcoal canister mounted either underhood or inside a fender, and from there up though the canister purge solenoid and into the intake manifold ........... and of course checking for problems along the way, starting in obvious places such as the canister purge solenoid (as has already been mentioned).

[deepsleep]

starting in obvious places .

Obvious? Hahaha. Dude, I couldnt even tell where the A/C unit was.

[1987cp]

:lol: Well, I guess that's where us other temperamental goons come in.

[gadget73]

There honestly isn't much to the evap system, but theres also not much point in my typing some long drawn out essay about where all the junk is and what to check if a gas cap replacement fixes it If that doesn't fix it, I promise the evap stuff won't be too bad. Mostly it will involve looking at a few hoses and making sure some stuff is plugged in properly.