On-Board Refueling Vapor Recovery (ORVR) System

On-Board Refueling Vapor Recovery (ORVR) System:

The On-board Refueling Vapor Recovery (ORVR) system is designed to recover the fuel vapors during a vehicle fueling operation. Instead of allowing fuel vapors to escape to the atmosphere, the ORVR system sends the vapor to the EVAP canister for use by the engine. The flow of liquid down the fuel filler neck provides a seal that prevents fuel vapor from leaving the fuel system. The ORVR system architecture varies across platforms. Some of the listed items are optional depending on the platform application. The following is a list of all the ORVR system components and a brief description of the component's operations:
^ The EVAP canister (1). The EVAP canister releases the fuel vapor into the engine through the EVAP control system.
^ The vapor lines (2). The vapor lines carry the fuel vapor from the fuel tank assembly to the EVAP canister.
^ The vapor recirculation line (3), if equipped. The vapor recirculation line carries the fuel vapor from the fuel tank to the top of the fuel filler pipe during fueling in order to reduce the fuel vapor at the canister. The vapor recirculation line is located on the inside of the fuel filler pipe or on the outside of the fuel filler pipe.
^ The variable orifice valve (4), if equipped. The variable orifice valve regulates the amount of the vapor that is allowed to enter the vapor recirculation line.
^ The fuel filler pipe (5). The fuel filler pipe carries the fuel to the fuel tank.
^ The check valve (6). The check valve limits fuel back-flow from the fuel tank during the fueling operation by allowing fuel flow only into the fuel tank. The check valve is located at the bottom of the fuel filler pipe or in the fuel tank filler neck.
^ The fuel sender assembly (7). The fuel sender assembly pumps fuel to the engine from the fuel tank.
^ The fill limiter vent valve (8). The fill limiter vent valve is located in the fuel tank and acts as a shut-off valve. The fill limiter vent valve performs the following functions:
- Controls the fuel tank fill level by closing the primary fuel tank vent.
- Prevents fuel from exiting the fuel tank through the vapor line and from entering the EVAP canister.
- Provides protection in the event of a vehicle roll-over by closing the vapor path from the fuel tank to the EVAP canister.
^ The vacuum relief valve (9), if equipped. The vacuum relief valve provides venting of excessive fuel tank pressure or vacuum. The vacuum relief valve is located in the fuel filler neck on a plastic fuel tank. The valve is in the fill limiter vent valve on a steel fuel tank.