Evaporative Emission Control Canister: Description and Operation

Fig 2 EVAP Canister:

EVAPORATION CONTROL SYSTEM
The evaporation control system prevents the emission of fuel tank vapors into the atmosphere. When fuel evaporates in the fuel tank, the vapors pass through vent hoses or tubes to a charcoal canister. The canister temporarily holds the vapors. Through the duty cycle EVAP purge solenoid, the PCM allows intake manifold vacuum to draw vapors from the charcoal canister into the combustion chambers during certain operating conditions. The solenoid regulates vapor flow from the canister to the engine.

The evaporative system uses specially manufactured hoses. If they need replacement, only use original equipment fuel vapor resistant hose.

EVAP CANISTER
All vehicles use a sealed, maintenance free, evaporative (EVAP) canister. Fuel tank pressure vents into the canister. The canister temporarily holds the fuel vapors until intake manifold vacuum draws them into the combustion chamber. The powertrain control module (PCM) purges the canister through the duty cycle EVAP purge solenoid. The PCM purges the canister at predetermined intervals and engine conditions.

The canister mounts to a bracket behind the front fascia on the passengers side of the vehicle (Fig. 2). The vacuum and vapor tube connect to the top of the canister.