On-Board Refueling Vapor Recovery System (ORVR)

The On-board Refueling Vapor Recovery (ORVR) system is used to recover fuel vapors during the vehicle re-fueling operation. The flow of liquid fuel down to the fuel tank filler neck provides a liquid seal. The purpose of the ORVR system is to prevent re-fueling vapors from exiting the fuel tank filler neck.

The ORVR components include:
1. The fuel tank which contains the modular fuel sender, the fuel limiter vent valve, and 3 rollover valves.
2. The fuel filler pipe, which carries fuel from the fuel nozzle to the fuel tank.
3. The EVAP canister receives refueling vapor from the fuel system, stores the vapor, and releases the vapor to the engine upon demand.
4. The vapor lines transport fuel vapor from the tank assembly to the EVAP canister.
5. The check valve limits fuel "spit-back" from the fuel tank during the refueling operation by allowing the fuel to flow only into the fuel tank. This check valve is located at the bottom of the fuel filler pipe.
6. The modular fuel sender assembly pumps fuel to the engine from the fuel tank.
7. The fill limiter vent valve acts as a shut-off 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.
8. The pressure/Vacuum relief valve provides venting of excessive fuel tank pressure and vacuum. The valve is located in the fuel tiller neck on a plastic fuel tank.
9. The vapor recirculation line is used to transport vapor from the fuel tank to the top of the fill pipe during the refueling in order to reduce vapor loading of the enhanced EVAP canister.
10. The variable orifice valve regulates the amount of vapor allowed to enter the vapor recirculation line.