Evaporative Emission (EVAP) Controls: Description
The EVAP controls minimize the amount of fuel vapor escaping to the atmosphere. Vapor from the fuel tank is temporarily stored in the EVAP control canister until it can be purged from the canister into the engine and burned.
- The EVAP control canister is purged by drawing fresh air through it and into a port on the intake manifold. The purging vacuum is controlled by the EVAP purge control solenoid valve, which is open whenever engine coolant temperature is above 154°F (68°C).
- When vapor pressure in the fuel tank is higher than the set value of the EVAP two way valve, the valve opens and regulates the flow of fuel vapor to the EVAP control canister.
- During refueling, the ORVR (Onboard Refueling Vapor Recovery) vent shut valve opens with the pressure in the fuel tank, and feeds the fuel vapor to the EVAP control canister.