Abstract: An evaporative emission control system for an internal combustion engine isolates the fuel tank from the engine during purging of a carbon canister used to store fuel vapor drawn from the fuel tank during refueling. The flow of vapor from the tank to the canister is controlled by a main vapor control valve, and the flow of vapor from the canister to the engine is controlled by a purge valve. Pressure transducers are used to independently sense vapor pressure in the tank and in the canister. An electronic controller operates the valves based in part on the pressure information generated by the pressure transducers.

Abstract: A fuel system, a method for operating the fuel system and a method for operating an engine which is supplied by the fuel system each comprise: (1) a fuel tank; (2) a fuel vapor tank in fluid communication with the fuel tank by means of a first fuel vapor conduit; and (3) an engine in fluid communication with the fuel vapor tank by means of a second fuel vapor conduit. Within each of the fuel system and the two methods, there is captured, contained and compressed within the fuel vapor tank a fuel vapor extracted from the fuel tank when either: (1) refueling the fuel tank whether or not the engine is operating; (2) when the engine is operating whether or not refueling the fuel tank; or (2) immediately after shutting down the engine after having operated the engine. The fuel vapor within the fuel vapor tank may then be employed alone for restarting the engine, in absence of liquid fuel from the fuel tank.