On-Board Refueling Vapor Recovery (ORVR) System

The On-Board Refueling Vapor Recovery (ORVR) system is an on-board vehicle system to recover fuel vapors during the vehicle refueling operation. The flow of liquid fuel down to the fuel tank filler neck provides a liquid seal. The purpose of ORVR is to prevent refueling vapor from exiting the fuel tank filler neck. The ORVR components are listed below, with a brief description of their operation:
^ The fuel tank-The fuel tank contains the modular fuel sender, the fuel limiter vent valve, and 3 rollover valves.
^ The fuel filler pipe-The fuel filler pipe carries fuel from the fuel nozzle to the fuel tank.
^ The Evaporative Emission ([1][2]EVAP) Canister-The EVAP canister receives refueling vapor from the fuel system, stores the vapor, and releases the vapor to the engine upon demand.
^ The vapor lines-The vapor lines transport fuel vapor from the tank assembly to the EVAP canister and engine.
^ The check valve-The check valve limits fuel spit-back from the fuel tank during the refueling operation by allowing fuel flow only into the fuel tank. The check valve is located at the bottom of the fuel filler pipe.
^ The modular fuel sender assembly-The modular fuel sender assembly pumps fuel to the engine from the fuel tank. The fuel tank pressure sensor is located on the modular fuel sender cover.
^ The Fuel Limiter Vent Valve (FLVV)-The FLVV acts as a shut-off valve. The FLVV is located in the fuel tank. This valve has the following functions:
- Controlling the fuel tank fill level by closing the primary vent from the fuel tank
- Preventing fuel from exiting the fuel tank via the vapor line to the canister
- Providing fuel spillage protection in the event of a vehicle rollover by closing the vapor path from the tank to the engine
^ The pressure vacuum relief valve-The pressure vacuum relief valve provides venting of excessive fuel tank pressure and vacuum. The valve is located in the fuel filler neck.
^ The vapor recirculation line-The vapor recirculation line is used to transport vapor from the fuel tank to the top of the fill pipe during refueling to reduce vapor loading to the enhanced EVAP canister.
^ The variable orifice valve-The variable orifice valve regulates the amount of vapor allowed to enter the vapor recirculation line.