Fuel systems

Claim 1

A DUAL PUMP FOR USE IN A FUEL SYSTEM FOR AN INTERNAL COMBUSTION ENGINE HAVING AN OVERFLOW TYPE OF CARBURETOR, SAID PUMP BEING ADAPTED TO PUMP FUEL FROM A FUEL TANK TO THE CARBURETOR AND TO SCAVENGE OVERFLOW FUEL FROM THE CARBURETOR AND PUMP IT BACK TO THE TANK, SAID PUMP COMPRISING A ROCKER ARM HOUSING, A ROCKER ARM PIVOTED IN SAID HOUSING, A PUMP HEAD ON SAID HOUSING, A CUP-SHAPED PUMP BODY SECURED TO SAID HEAD, SAID BODY HAVING A CENTRAL HUB WITH AN AXIAL OPENING, A DIAPHRAGM HAVING A CENTRAL HOLE REGISTERING WITH THE OPENING IN THE HUB, THE DIAPHRAGM HAVING ITS INNER MARGIN AROUND ITS CENTER HOLE SEALED TO THE HUB AROUND THE OPENING IN THE HUB AND HAVING ITS OUTER MARGIN CLAMPED BETWEEN THE BODY AND THE HEAD WITH AN INTERMEDIATE ANNULAR PORTION OF THE DIAPHRAGM BETWEEN THE HUB AND THE CLAMPED MARGIN OF THE DIAPHRAGM CONSTITUTING AN ANNULAR SLACK LOOP FREE FOR FLEXURE, THEREBY PROVIDING A PRIMARY PUMP CHAMBER ON THE SIDE OF THE DIAPHRAM, TOWARD THE BODY, SAID BODY HAVING A VALVED INLET AND A VALVED OUTLET FOR SAID PRIMARY CAMBER, A CUP-SHAPED CASING HAVING A RIM PORTION SECURED IN SEALED RELATION TO THE LOOP ON THE OTHER SIDE OF THE DIAPHRAGM AND PROVIDING A SCAVENGER PUMP CHAMBR BETWEEN THE CASING AND THE DIAPHRAGM, SAID BODY HAVING A VALVED INLET AND A VALVED OUTLET IN COMMUNICATION WITH SAID SCAVENGER CHAMBER VIA SAID OPENING IN THE HUB, A ROD SECURED TO SAID CASING AND EXTENDING INTO SAID ROCKER ARM HOUSING, SAID ROCKER ARM BEING ADAPTED TO MOVE SAID ROD IN THE DIRECTION AWAY FROM SAID BODY, AND A COMPRESSION SPRING IN SAID HEAD SURROUNDING SAID ROD BIASING SAID CASING IN THE OPPOSITE DIRECTION.