Evaporative Emissions System: Description and Operation

EVAPORATIVE AND ORVR EMISSION CONTROL SYSTEM
On-Board Refuelling Vapor Recovery (ORVR) system is properly designed to prevent the fuel tank vapor (HC) emission during refueling at the gas station.

This system consists of fill vent valve (ORVR), fuel shut-off valve, fuel cut valve (roll over), fuel liquid/vapor separator which is installed on the fuel tank, charcoal canister which is mounted under the rear floor LH side member with protector, tubes and miscellaneous connection.

During refueling, the flow and column of the refueling fuel draws the ambient air into the filler pipe so as not to emit fuel vapor in the air. The fuel vapor in the tank is then forced to the canister via the fill vent valve and the fuel liquid/vapor separator which isolates liquid fuel ingredient and transfers the pure vapor to the carbon canister.

While the engine is operating, the trapped vapor emission in the canister is drawn and fed by the intake manifold vacuum into the engine combustion chamber. According to this purge process, the carbon canister is purged and recovers its absorbing capability.