Evaporative Emissions System: Description and Operation

The evaporative emissions system:
- prevents hydrocarbon emissions from reaching the atmosphere.
- stores fuel vapors in the evaporative emissions canister.
- returns the stored fuel vapors to the engine during engine operation.

The fuel vapors are routed:
- from the fuel tank through the two evaporative emissions valves.
- to the evaporative emissions canister through a vapor line.
- to the engine when the evaporative emission canister purge valve is opened by the Powertrain Control Module (PCM).

The fuel tank pressure sensor:
- monitors the fuel tank pressure.
- displays the pressure reading during OBD-II testing.

The fuel tank filler cap:
- relieves system pressure above 14 kPa (2 psi).
- relieves system vacuum negative 3.8 kPa (0.53 psi).

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

The evaporative emissions canister:
- is located along the left frame rail behind the fuel tank.
- contains activated carbon.
- stores fuel vapors.

The evaporative emissions canister vent valve:
- seals the evaporative emissions systems for the OBD II leak check.
- is mounted on the evaporative emissions canister.
- is serviced as a separate item.