On-Board Refueling Vapor Recovery System (ORVR)

The On-board Refueling Vapor Recovery System (ORVR) is an on-board vehicle system designed to recover fuel vapors during the vehicle refueling operation. The flow of liquid fuel down the filler neck provides a liquid seal which prevents vapor from leaving the fuel system by transporting vapor to the EVAP canister for use by the engine. The

ORVR system architecture varies by platform. Some of the items listed below are optional depending on the platform application. Listed below are all the ORVR system components with a brief description of their operation:
^ EVAP Canister (1) - the EVAP canister receives refueling vapor from the fuel system, stores the vapor and releases the vapor to the engine upon demand.
^ Vapor Lines (2) - transports fuel vapor from the tank assembly to the EVAP canister.
^ Vapor Recirculation Line (3) (Optional) - this line is used to transport vapor from the fuel tank to the top of the fuel filler pipe during refueling to reduce the fuel vapor to the canister. This line can be located inside the fuel filler pipe or outside of the fuel filler pipe.
^ Variable Orifice Valve (4) (Optional) - the valve regulates the amount of vapor allowed to enter the vapor recirculation line.
^ Fuel Filler Pipe (5) - the pipe which carries fuel from the fuel nozzle to the fuel tank.
^ Check Valve (6) - the check valve limits fuel "spitback" from the fuel tank during the refueling operation by allowing fuel flow only into the fuel tank. This check valve is located at the bottom of the fuel filler pipe.
^ Modular Fuel Sender Assembly (7) - this assembly pumps fuel to the engine from the fuel tank.
^ Fuel Limiter Vent Valve (8) (FLVV) - this valve acts as a shutoff valve located in the fuel tank and has the following functions:
- Controls the fuel tank fill level by closing the primary vent from the fuel tank.
- Prevents fuel from exiting the fuel tank via the vapor line to the canister.
- Provides fuel-spillage protection in the event of a vehicle rollover by closing the vapor path from the tank to the EVAP canister.
^ Pressure/Vacuum Relief Valve (9) (Optional - the pressure/vacuum relief valve provides venting of excessive fuel tank pressure and vacuum. The valve is located in the fuel filler neck on a plastic fuel tank and in the Fuel Limiter Vent Valve (FLVV) on a steel fuel tank.