I have 2004 H2 and I can't fill at the pump. I have no codes and changing the canister vent valve did nothing. Do charcoal canister go bad on a hummer? . where do I look form here?

 

Needs better explanation. What do you mean by “cant fill at the pump”?

 

That does sound like the canister is somehow filled or the tube to it is clogged.

Aside from that, never top off past a pump click or two as that does risk fuel going into the canister.

 

 

Thanks for sharing Hummerz, informative
Yes, the charcoal canister can become plugged and cause filling issues, along with a plugged filter and passages on the vent valve, an issue I had to deal with on my 08
Typically you can pull the canister off and shake it and it should rattle, filled with little beads of charcoal, mine was solid and would not rattle and as you I was having trouble filling my tank.
GM issued a re-design/relocation of the vent solenoid intake away from road dust to help with plugging

Neal

 

Is there a way to disconnect the fuel vent line from the tank to the charcoal canister, go fill up, and see if the charcoal canister is bad?

 

i had an old 86 jag that the canister would plugg up every so often. i would whack it with a rubber mallet till i could hear the charchole bouncing around again. they usually get caked up from overfilling the gas tank.

 

I've had to do the same thing

Neal

 

Yes, yet you will get the CEL P0455 code.

 

Thanks for all the answers guys. I will get a new charcoal filter and try it.