Hi everyone

This is my 1st time posting here ,but i have used the forum to help with me various issues throughout the years.
The problem i am having is it is hard to fill the truck with gas. The pump clicks off after half a gallon or so. Taking 20 minutes just to get a half tank.

I get a "tighten gas cap" message on the DIC periodically. I do not have any other trouble codes present. I have confirmed the evap charcoal canister is bad. By the presence of charcoal pellets in the line of the canister purge valve in the engine bay.

My question is how do i confirm it is only the evap canister that is bad ,and when i blow the lines out do i need to disconnect them from the fuel tank.
I have access to a bidirectional scanner as well as a cheap smoke machine.

Thanks in advance for the help

 

I would disconnect the hoses at the cannister end, and blow back from the other ends if you can, before putting the new canister in.

Normally if the purge solenoid or vent solenoid fail, they throw a code. They don't cost that much, so you might want to just replace them all, as it is possible gas got through the tubes and saturated/clogged things. I had to use heater hose (5/8 maybe?) to replace the tube to the solenoid next to the gas tank, as the original GM one had the tube as part of the assembly, and the affordable replacement did not.

The key long term is to be sure NOT to overfill the tank into the neck. I stop now the first time the pump fill handle clicks off, and resist the urge to fill until it is up into the neck. That avoids spill over into that vent tube that goes back down to the canister.

 

Everything is more expensive these days.....

 

I ended replacing the charcoal canister on my 2007 Tahoe. The foam filters deteriorated and let the charcoal grains get in the vent lines and clog up everything.I also replaced that vent valve back there also because it had pellets in it. When filling your tank, stop when the gas nozzle shuts off and don't try to put in an extra gallon.