Running Loss System

The evaporative loss control system prevents unprocessed vapour emitted from the fuel tank from entering the atmosphere.

A running-loss control valve (4.0 liter NAS markets only) or a tank pressure control (Rochester) valve (where fitted) is installed between the fuel tank and the carbon canister.

Both valves are normally closed, but open during engine operation. They vent vapours from the fuel tank to the carbon canister(s).

On filling up the tank the fuel produces positive pressure inside the tank which causes only the running loss valve to close, blocking off the vent line. The Rochester valve is closed when the engine is off.

The purge valve is controlled by the engine control module (ECM) and is linked to the carbon canister.