See Figure 1
The canister functions to cycle the fuel vapor from the fuel tank (and the float chamber on the carbureted models) into the intake manifold and eventually into the cylinders for combustion. The activated charcoal element within the canister acts as a storage device for the fuel vapor at times when the engine operating condition will not permit fuel vapor to burn efficiently.
Fuel vapors trapped in the sealed fuel tank are vented through the orifice's vapor valve assembly in the top of the tank. The vapors leave the valve assembly through a single vapor line and continue to the carbon canister for storage until they are purged to the engine for burning.
The carbon canister contains activated carbon, which absorbs the fuel vapor. The canister is located in the engine compartment or along the frame rail. The only required service for the evaporative emissions canister is a regular inspection of the canister. If the charcoal canister is gummed up, cracked or saturated with fuel, the entire canister should be replaced.