I have a 2004 avalanche 4x4 5.3 with 145,000, when filling the tank with fuel it fills as should but when it gets full and kicks the pump off it back flushes gas all over ground,as your filling and you stop,you will hear air come out of filler neck two seconds after stoping,I have replaced ,charcoal canster and vent solenoid, and purge valve solenoid, I blew air threw lines when replacing these also,is there anything else I can do or check besides just not filling my tank all the way.thanks for any help