Evaporative Emissions System: Description and Operation

The evaporative emission system:
^ prevents hydrocarbon emissions from reaching the atmosphere.
^ stores fuel vapors in the Evaporative Emission (EVAP) canister.
^ returns the stored fuel vapors to the engine during engine operation.
^ has an evaporative emission test port for test purposes.

The fuel vapors are routed:
^ from the fuel tank through the fuel vapor valve tube assembly to the evaporative emission canister.
^ to the engine when the Evaporative Emission (EVAP) canister purge valve is opened by the Powertrain Control Module (PCM).
^ during fueling, vapors are routed through the fuel vapor control valve tube assembly to the evaporative emission canister. (On-Board Refueling Vapor Recovery (ORVR) only).

The fuel tank pressure sensor:
^ senses the pressure levels in the fuel tank.
^ provides the pressure reading to the PCM during the OBD II Test.

The evaporative emission canister:
^ is located near the rear of the vehicle.
^ contains activated carbon.
^ stores fuel vapors.

The fuel tank filler cap:
^ relieves system pressure above 13.7 kPa (2 psi).
^ relieves system vacuum at 3.4 kPa (0.55 psi).

The canister vent solenoid:
^ seals the evaporative emission system for the OBD II Leak Test.
^ is mounted to the evaporative emissions canister.
^ is repaired as a separate item.

The evaporative emission canister purge valve:
^ regulates purging of the evaporative emission canister.
^ is controlled by the powertrain control module.
^ contains the evaporative emission test port.

The liquid/vapor fuel discriminator assembly:
^ prevents liquid fuel suspended in the fuel vapor from being drawn into the evaporative emission canister along with the fuel vapors.
^ returns the liquid to the tank.