Evaporative Emission Systems: Overview
WARNING: This page does not describe the selected car, but rather 30 other vehicles, including the 2004 Mercury Sable, 2004 Mercury Mountaineer, 2004 Mercury Monterey, 2004 Mercury Marauder, and 2004 Mercury Grand Marquis. However, it is still accessible from the selected car via links, so may be relevant.
The Evaporative Emission (EVAP) system prevents fuel vapor build-up in the sealed fuel tank. Fuel vapors trapped in the sealed tank are vented through the vapor valve assembly on top of the tank. The vapors leave the valve assembly through a single vapor line and continue to the EVAP canister for storage until the vapors are purged to the engine for burning.
All applications required to meet OBD-II regulations, utilize the Enhanced Evaporative Emission (EVAP) System. Some applications also incorporate an On Board Refueling Vapor Recovery (ORVR) System. Refer to the appropriate EVAPORATIVE EMISSIONS article for vehicle specific information.