2005 Chevy Avalanche gas filler pipe not venting. Fill nozzle clicks off after pumping just a couple of seconds. From researching, it could be several things from the gas cap to the evap surge valve under the hood to the evap cannister at the gas tank. I have an appointment tomorrow at a trusted shop to have it looked at but I don’t want to just start throwing parts at it. I have tightened the gas cap but I feel it’s downstream from the cap as it still won’t take gas after trying to fill at different pumps several times. Can you guys suggest what the most likely culprit might be?