I have a 2005 Chevrolet Tahoe Z71. Lately I cannot fill the tank but half gallon or soo at a time. I replaced the purge solenoid, vapor canister and the vent valve next to the vapor canister. The line between the two is not clogged, however, when I took off the vapor canister I notice small black beads falling out. When I replaced the purge solenoid I noticed the same beads when I disconnected the line. After replacing all three parts I still cannot put gas in but half gallon at a time. There are no engine lights or codes displayed Don't know what else to do. HELP

 

check the line from the tank to the canister. the tank to the canister to the vent valve and vent filter and all the connecting hoses must be clear to vent the tank when filling.
the entire system should be disconnected and all of the canister beads removed.