Have a [COLOR=blue! important][COLOR=blue! important]2006 [COLOR=blue! important]GMC[/COLOR][/COLOR][/COLOR] Serria. Have been driving around with a check [COLOR=blue! important][COLOR=blue! important]engine [COLOR=blue! important]light[/COLOR][/COLOR][/COLOR] for some time. It is a p0455 EVAP large leak detected. I have been trying to get a smoke tester to find the leak. I now also have a problem filling the tank. I get spit back while fueling. Have resorted to filling with a funnel to cut down on fill time. Do you think it could be a vent valve? Any suggestions?