The charcoal canister is used as an emission control device and consists of a sealed canister of activated charcoal with connections on the top of the canister. It’s used as a temporary storage device for fuel vapor from the fuel tank.
When the engine is stopped, vapor from the tank passes through the systems vent pipe into the canister where it is absorbed by the charcoal.
When the engine is running, the lower pressure in the inlet manifold draws in the gasoline vapor out of the charcoal, into the intake manifold.
The process is controlled so it doesn’t upset the normal operating air-fuel mixture.
