Trying to diagnose an EVAP issue.

[Fireball5657]

This is my first post on this forum, so if I'm in the wrong place, feel free to let me know.

Hello all, my Suburban has been doing the dreaded "kicking off after a gallon of fuel" and I am trying to diagnose why. I do have a code P0449, which is for the vent solenoid, but I have disconnected the hose that goes to the vent solenoid and it still kicks off after a gallon or so. I took the small hose from the canister to the solenoid off, cleaned it out, and it still won't work. I decided to go farther in the system and disconnect the hose that goes from the tank to the canister on the canister side, but it didn't change anything. Now, my diagnostic skills may be a little off, and I've never done EVAP system work before, but at this point it has to be either the sender or the hose from the tank to the canister right? And if it is that hose from the tank to the canister, is there any way to clean it out without taking it off the tank?

The Suburban in question is a 1500 2005 model with the L59. Should be the one in my signature if I set that up correctly.

 

[Scottydoggs]

most of the time this is caused by a faulty fuel vapor canister. they are filled with charcoal pellets and they break free and clog the vent lines.

heres a vid.

 

[Fireball5657]

most of the time this is caused by a faulty fuel vapor canister. they are filled with charcoal pellets and they break free and clog the vent lines.

heres a vid.

I haven't ruled that out yet, but with the hose from the tank to the canister disconnected, shouldn't that rule out the canister being the main issue? It could be multiple things that have gone bad, I'm definitely keeping that in consideration, but I think there's something farther up in the system that's acting up. The hose from the canister to the vent solenoid didn't have any pellets in it when I took it out, just a bit of red Oklahoma dirt. I also really don't want to spend the $100 on a new canister if I can help it. I'm sure I'll have to eventually, but unless it is somehow the problem, I'd like to just leave it alone for now.

 

[Scottydoggs]

if you take your canister off and its lines. if you find its full of gas and the lines have them pellets in them, the canister broke for sure.

 

[Fless]

A few tips in the thread below; one is to blow through the canister to be sure it's not plugged.

2005 Tahoe gas filling / purge canister - clearing lines of carbon

2005 Tahoe 5.3 but not flex Today, we noticed that when trying to fill the gas tank that the system is not working as normal and the gas pump keeps kicking off after 1/2 gallon or so unless you fill it very slowly. Reading on this site it seems like culprits are problems with potentially evap...

www.tahoeyukonforum.com

 

[B-train]

The PO449 refers to the vent solenoid I believe. I had the same issue on my 07 denali and it drove me nuts. I replaced the charcoal canister and vent....no fix. I went to advance auto and bought the vent solenoid for under the hood. Fixed and then not. My dad owns a repair shop, so we used rhe scanner and commanded the solenoid to open and it was defective from the factory. Buy AC DELCO parts the first time if it's anything electronic related and save yourself the headache!!! Put in OEM part and hasn't had an issue since.

Also to note, when the system is working correctly and you are refueling with it running, you will hear the motor change sound/rpm as the vent line pulls a vacuum on the tank as it fills to make room. Computer turns it off and on based on tank pressure and fuel level when filling I believe.

Hope this helps!