Unable to fill the tank and had "check gas cap" message. Code was P0455.

Replaced the evac canister with ACDelco 214-2149

Problem still exists. Where to now??

Thanks Donald

May have to work in stages.....

Disconnect the line from the tank that goes to the canister, and try to fill....if ok....reattach and disconnect line from canister to purge solenoid....if ok , reattach then disconnect line from canister to purge solenoid at the solenoid....if ok, then it'* the purge......

I disconnected, from the canister, the line to the tank and also the line to the solenoid. Still unable to fill without constant shut off by the pump. I was unsuccessful in removing the third line, so I just replaced purge valve. The same condition still exists. Where to next, the fill hose??