Servicing the carbon canister is only necessary if it is clogged or contains liquid fuel, indicated by odor or by excessive weight. Remove the canister and blow into the air vent in the bottom of the canister. If air passes from the fuel vapor inlet and the canister does not contain liquid fuel, it is okay. If replacement is necessary, the canister must be replaced as a unit; it cannot be disassembled. For further evaporative emission control system testing, refer to Section 4.