Evaporative Emission Control (EVAP) System

Evaporative Emission Control System Schematic:

PURPOSE
The Evaporative Emission (EVAP) control system used on all vehicles is the charcoal canister storage method. This method transfers fuel vapor from the fuel tank to an activated carbon (charcoal) storage device (canister) to hold the vapors when the vehicle is not operating. When the engine is running, the fuel vapor is purged from the carbon element by intake air flow and consumed in the normal combustion process.

OPERATION
This system has a remote mounted canister purge control solenoid valve. The Powertrain Control Module (PCM) operates this solenoid valve to control vacuum to the canister. Under cold engine or idle conditions, the solenoid valve is closed, which prevents vacuum from being applied to the canister.

RESULTS OF INCORRECT SYSTEM OPERATION
^ Poor idle, stalling and poor driveability can be caused by:
- Inoperative cannister purge solenoid valve.
- Damaged canister.
- Hoses split, cracked and, or not connected to the proper tubes.

^ Evidence of fuel loss or fuel vapor odor can be caused by:
- Liquid fuel leaking from fuel lines.
- Cracked or damaged canister.
- Inoperative canister control valve.
- Disconnected, misrouted, kinked, deteriorated or damaged vapor hoses, or control hoses.