On-Board Refuelling Vapor Recovery System (ORVR)

On-Board Refueling Vapor Recovery System (ORVR):

1999 Eldorado and Deville vehicles built after March 1, 1999 will have fuel system components identified with RPO's NAC/RB1. These vehicles will feature the On-Board Refueling Vapor Recovery System (ORVR).

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 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 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 Fuel Sender (fuel tank pressure sensor located on modular fuel sender cover)
^ Fuel Limiter Vent Valve (FLVV)
^ Pressure Relief Valve
^ Vapor Recirculation Line
^ Variable Orifice Valve

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 a roll over valve integral to the modular fuel sender.
^ 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 integral to the fuel tank filler inlet.
^ 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 Valves - the pressure/vacuum relief valves provide venting of excessive fuel tank pressure and vacuum. The pressure relief valve is located on the top center of the tank. The vacuum relieve valve is integral to the fuel cap located at the top of the fill pipe.
^ 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 venting to the canister when the FLVV is in its shut-off condition.