O.K. guys, the charcoal canister is equipped with a check valve that incorporates two check balls. Depending on the running conditions and the pressure in the fuel tank, the check balls open and close the passageways to the throttle body and fuel tank. The book says that poor idle, stalling, and poor drivability can be caused by an inop check valve, a damaged canister, split or cracked hoses or hoses connected to wrong fittings. My guess is a clogged canister filter or a sticking check valve, both of which are internal to the canister, is the source of your buzzing noise. I can find no info on repairing the canister, and I believe it is a sealed unit. The book says to replace if defective or clogged. Hope this info helps.........