On-Board Refueling Vapor Recovery System (ORVR)

DESCRIPTION
The On-Board Refueling Vapor Recovery System (ORVR) is an on-board vehicle system 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 (ORVR) is to prevent re-fueling vapor from exiting the fuel tank filler neck.

The ORVR components include:

^ Fuel Tank
^ Fuel Tank Filler Pipe
^ EVAP Canister
^ Vapor Lines
^ Check Valve
^ Modular Fuels Sender (fuel tank pressure sensor located on modular fuel sender cover)
^ Fuel Limiter Vent Valve (FLVV)
^ Pressure Vacuum Relief Valve
^ Vapor Recirculation Line
^ Variable Orifice Valve

OPERATION
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. Listed below are the ORVR system components with a brief description of their operation:

Fuel Tank
Contains the modular fuel sender, fuel limiter vent valve, and three rollover valves.

Fuel Filler Pipe
The pipe which carries fuel from the fuel nozzle to the fuel tank.

EVAP Canister
The EVAP canister receives refueling vapor from the fuel system, stores the vapor and releases the vapor to the engine upon demand.

Vapor Lines
Transports fuel vapor from the tank assembly to the EVAP canister.

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. This check valve is located at the bottom of the fuel filler pipe.

Modular Fuel Sender Assembly
This assembly pumps fuel to the engine from the fuel tank.

Fill Limiter Vent Valve (FLVV)
This 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.

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 on a plastic fuel tank.

Vapor Recirculation Line
The vapor recirculation line is used to transport vapor from the fuel tank to the top of the fill pipe during the refueling to reduce vapor loading to the Enhanced EVAP canister.

Variable Orifice Valve
The variable orifice valve regulates the amount of vapor allowed to enter the vapor recirculation line.