I have a 08 Envoy, 4.2, Auto. 4 wheel drive. After i had to have the shop install a new fuel pump, i can not get the tank full of fuel with out the pump kicking off several times. The shop told me it was the vapor canister purge valve. so i replaced that, still no change, no check engine light. I lowered the fuel tank to make sure there was no lines that were kinked, none. Next, i replace the charcoal canister, still no good, still cant pump gas with out taken 30 minutes to get a full tank.I call the shop back up and now they tell me that they dont want to see it back. So what i am i overlooking? All lines are in great shape, all clips are in place and holding good.Thank you for reading this.