Fuel overflow into evap canister

I filled up my truck's tank on Thursday evening Feb 5th, and like normal I fill it all the way up to the neck. After it stopped automatically, I got an extra 4.1 gallons in until was up to the neck. After that, I drove abt 1 mile back home and parked it. Come Sunday morning I see that fuel has leaked out of the breather hole on the top of the evap canister. I removed the Purge line from the canister to the valve and the pressure was released, causing some more fuel to leak out. I then cracked open the fuel cap to release the pressure there, and the leakage stopped. I removed the canister and used low-pressure compressed air to clear out the remaining liquid gas.

It was abnormally warm on Saturday (near 60°) so my guess is that the fuel expanded from the cold Thursday night (near 25°) and flowed into the evap canister since it had nowhere else to go.

I guess my question is, should there be some check valve that prevents liquid fuel from entering the evap canister via the tubing? From what I know, that tube was to help suck fuel vapors from the tank, but not allow liquid to get in. Would appreciate enlightenment. Or mebbe I should just drive it further after a fill-up....

[quote=jdmccright;5913847]I filled up my truck's tank on Thursday evening Feb 5th, and like normal I fill it all the way up to the neck. After it stopped automatically, I got an extra 4.1 gallons in until was up to the neck. After that, I drove abt 1 mile back home and parked it. Come Sunday morning I see that fuel has leaked out of the breather hole on the top of the evap canister. I removed the Purge line from the canister to the valve and the pressure was released, causing some more fuel to leak out. I then cracked open the fuel cap to release the pressure there, and the leakage stopped. I removed the canister and used low-pressure compressed air to clear out the remaining liquid gas.

It was abnormally warm on Saturday (near 60°) so my guess is that the fuel expanded from the cold Thursday night (near 25°) and flowed into the evap canister since it had nowhere else to go.



this is exactly what NOT to do.....It is well known that this filling too much and then parking the vehicle after a short run is sure to cause your problem...ya there are componets that are in the fuel system to prevent this BUT when the pressure gets high the gas blows out...and the cannister gets damaged....

when the liquid expands to the point of no vapor/air you get a huge amount of pressure build up...the system must vent this or ka boom.........

it is very possible the cannister is now defective but maybe you lucked out...

Hmmm...welp, guess I learned something new. Done it for years in my Toy with no ill effects, so didn't think twice about it for the truck. Guess I'll plan on getting 30-40 miles less distance from now on and hope it clears out...no CEL thank God. Thanks!

Hmmm...welp, guess I learned something new. Done it for years in my Toy with no ill effects, so didn't think twice about it for the truck. Guess I'll plan on getting 30-40 miles less distance from now on and hope it clears out...no CEL thank God. Thanks!


looks like you lucked out...try to fill up as you start your trip..that's what I do, when I'm looking for a long amount of miles to be covered..