Evaporative Emission Control System Description: Notes

The evaporative emission system is used to reduce hydrocarbons emitted into the atmosphere from the fuel system. This reduction of hydrocarbons is accomplished by activated charcoals in the EVAP canister. The fuel vapor in the sealed fuel tank is led into the EVAP canister which contains activated carbon and the vapor is stored there when the engine is not operating or when refueling. The vapor in the EVAP canister is purged by the air through the purge line to the intake manifold when the engine is operating. The EVAP canister purge volume control solenoid valve is controlled by the Engine Control Module. When the engine operates, the flow rate of vapor controlled by the EVAP canister purge volume control solenoid valve is proportionally regulated as the air flow increases. The EVAP canister purge volume control solenoid valve also shuts off the vapor purge line during decelerating and idling.

Poor idle, stalling, and poor driveability can be caused by the following conditions:

• An inoperative EVAP emission canister purge solenoid valve
• A damaged canister
• Hoses that are split, cracked, or not connected to the proper tubes