Vapor charcoal canister
 

2005 Tahoe, I have replaced the vent solenoid and the charcoal canister. Both new GMC parts. Went to fill with gas and it still stops at 1 gallon give or take and spills out...What else is there? The replacing these parts was suppose to fix the problem but it didn't even help filling the tank at all. Any suggestions as to what is causing the gas pump handle to still shut off and gas spill out? Can't get more than a gallon in at a time, I have noticed a little bit of a faint whistle sound just before it spills gas.
Thanks

the tank vents out a hose to the canister, out the vent solenoid, out to a filter. the entire path must be free of restrictions.