On-Board Refueling Vapor Recovery System (ORVR)

The On-board Refueling Vapor Recovery System (ORVR) is an onboard 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. Listed below are 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.
^ Fuel filler pipe (3)- the pipe which carries fuel from the fuel nozzle to the fuel tank.
^ Check valve (4)- 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 (5)- this assembly pumps fuel to the engine from the fuel tank.
^ Fill limiter vent valve (FLVV) (6)- 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 (Optional)(7) 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 Fill Limiter Vent Valve (FLVV) on a steel fuel tank.

NOTE: Do not use fuels containing methanol in order to prevent damage and corrosion to the fuel system.

The fuel supply is stored in the fuel tank. An electric fuel pump, which is located in the fuel tank with the fuel level sensor sending unit, pumps fuel through an in-line fuel filter to the engine. The pump provides fuel at a pressure greater than is needed by the injectors. The fuel pressure regulator keeps fuel available to the injectors at a regulated pressure. The unused fuel is returned to the fuel tank by a separate line.