Abstract: Apparatus for supplying air-and-gasoline vapor mixture from the ullage space in a gas tank above the gasoline therein through a safety cannister and a shut-off valve to two "gang" valve assemblies that divide the vapor into individual flows that are delivered directly to the intake valves of the individual cylinders of a piston-and-cylinder engine, by-passing the carburetor and the intake manifold. The gas tank is aerated through a vent pipe having on one end an air filter open to outside air and on the other end an aerator submerged in the gasoline, and the fuel-vapor mixture is directed into the intake ports of the intake valves by heat-resistant nozzle tubes.

Abstract: A method and apparatus for increasing fuel economy of a diesel fuel engine in which an aerator (40) bubbles air through diesel fuel (F) in a diesel fuel tank (T) to generate diesel fuel fumes in the ullage (U). In a turbocharged diesel engine, the fumes are directed by a valve (60) to fume injectors 86 and injected just before the turbo charger fan (32). In a normally aspirated engine, the fumes are directed by a valve (160) to the intake manifold (124).