A PRIMING SYSTEM FOR FLOAT-TYPE CARBURETORS, IN WHICH A FUEL ENRICHMENT PASSAGE CONNECTS THE FLOAT CHAMBER WITH THE INDUCTION PASSAGE ON THE ENGINE SIDE OF THE THROTTLE VALVE AND AN AIR PASSAGE CONNECTS THE FUEL ENRICHMENT PASSAGE WITH THE INDUCTION PASSAGE NEAR THE AIR INTAKE THEREOF. A VALVE IDSPOSED IN THE FUEL ENRICHMENT PASSAGE POSTERIOR TO THE AIR PASSAGE IS AUTOMATICALLY CONTROLLED BY A BIMETALLIC ELEMENT AND A SOLENOID FOR CONTROLLING THE FUEL-AIR MIXTURE SUPPLIED TO THE INDUCTION PASSAGE IN ACCORDANCE WITH THE ENGINE TEMPREATURE.