Evaporative Emissions System: Description and Operation

The evaporative emission system:
^ Prevents hydrocarbon emissions from reaching the atmosphere.
^ Stores fuel vapors in the evaporative Emissions Canister (EVAP canister).
^ Returns the stored fuel vapors to the engine during engine operation.
^ Has an evaporative emission test port for test purposes.
^ Has a canister vent solenoid remote vent hose normally routed into a hole in the rear LH frame rail.

The fuel vapors are routed:
^ From the fuel tank through the fuel vapor control valve tube assembly.
^ Vapors are then routed through the EVAP canister purge outlet tube to the engine when the evaporative emission canister purge valve (EVAP canister purge valve) is opened by the Powertrain Control Module (PCM).

The fuel tank pressure sensor:
^ Monitors the pressure in the fuel tank.
^ Provides a fuel tank pressure reading to the powertrain control module during the OBDII Test.

The evaporative emissions canister:
^ Is located near the rear of the vehicle.
^ Contains activated carbon.
^ Stores fuel vapors.

The evaporative emissions canister and bracket assembly:
^ Includes the fuel vapor hose assembly, wire harness, foam pad, 2.0L canister, canister vent solenoid, and vent hose assembly.
^ Is located near the rear of the vehicle.

The fuel tank filler cap:
^ Relieves system pressure above 14 kPa (2 psi).
^ Relieves system vacuum at 3.8 kPa (0.55 psi).

The canister vent solenoid:
^ Seals the evaporative emissions system for the OBDII leak check.
^ Is mounted to the evaporative emissions canister.
^ Is serviced as a separate item.

The evaporative emission canister purge valve:
^ Regulates purging of the evaporative emissions canister.
^ Is controlled by the powertrain control module.

Fuel vapor control valve tube assembly:
^ Consists of the fuel tank mounted fuel vapor vent valve and hose assembly.
^ Prevents suspended liquid fuel from being drawn into the evaporative emission canister along with the fuel vapors.
^ Returns the liquid to the tank.

Fuel vapor control valve:
^ Is mounted to the fuel tank.
^ Attaches to the fuel vapor control tube assembly.