On-Board Refueling Vapor Recovery System (ORVR)

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 fuel filler pipe provides a liquid seal which prevents vapor from leaving the fuel filler pipe. An EVAP pipe transports the fuel vapor to the EVAP canister for use by the engine. Listed below are the ORVR system components with a brief description of their operation:
^ The 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.
^ The EVAP pipes (2)-transports fuel vapor from the fuel tank to the EVAP canister.
^ The fuel filler pipe (3)-the pipe which carries fuel from the fuel nozzle to the fuel tank.
^ The check valve (4)-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.
^ The modular fuel sender assembly (5)-this assembly pumps fuel to the engine from the fuel tank.
^ The Fill Limiter Vent Valve (FLVV) (6)-this valve acts as a shut off valve. The FLVV is located on the top of the right fuel tank. This valve is not serviced separately. The FLVV has the following functions:
- Controls the fuel tank fill level by closing the primary vent from the fuel tank.
- Prevents the fuel from exiting the fuel tank via the EVAP pipe to the canister.
- Provides fuel-spillage protection in the event of a vehicle rollover by closing the vapor path from the fuel tank to the EVAP canister.

The fuel metering system consists of the following components:
^ The fuel supply components, including:
- 2 fuel tanks
- A modular fuel pump and sender assembly
- A siphon jet pump and sender assembly
- A fuel filter/pressure regulator assembly
- The fuel pipes and hoses
^ The fuel pump electrical circuit
^ The fuel rail assembly, including:
- The fuel injectors
- The fuel pulse dampener
^ The throttle body assembly, including:
- The Throttle Position (TP) sensor
- The throttle actuator motor