Fill Control Vent System

Fill limiting is accomplished through fill pipe configuration or external vent tubes within the fuel tank filler pipe (9034) and fuel tank (9002). The vent system is designed to permit at least 10 percent fuel tank volume air space when the fuel tank is filled to capacity. This air space provides for thermal expansion of fuel, as well as being an aid to the in-tank vapor vent system.

This system provides a vapor space above the gasoline surface in the fuel tank. This area is sufficient to permit adequate breathing space for the evaporative emission valve (9B593) under static and most dynamic conditions. This is accomplished by the evaporative emission valve that is centrally located on the upper surface of the fuel tank.

All evaporative emission valves make use of a small orifice in order to allow only vapor and not fuel to pass into the tube running forward to the evaporative emissions canister (EVAP canister) (9D653). On all vehicles, the assembly mounts directly to the top of the fuel tank using a fuel vapor separator seal.

Fuel vapors trapped in the sealed fuel tank are vented through the orificed evaporative emission valve in the top of the fuel tank. The vapors leave the evaporative emission valve through a single vapor tube and continue to the evaporative emissions canister for storage, until they are purged to the engine (6007).