DECELERATION ENRICHMENT FUEL SYSTEM FOR AN INTERNAL COMBUSTION ENGINE

The internal combustion engine includes a carburetor having an air induction passage communicating with the engine combustion chamber and a throttle valve mounted inside the induction passage for pivotal movement between an idling speed position and a range of high speed positions. a primary fuel delivery system including a fuel pump for supplying fuel to the carburetor during normal engine operation, and a secondary fuel delivery system for supplying a flow of enrichment fuel to the engine combustion chamber, independently of the primary fuel delivery system. during periods of rapid engine deceleration. The secondary fuel delivery system includes conduit means communicating with the fuel pump and with the combustion chamber at a point downstream of the throttle valve, a solenoid-actuated valve movable between a normally closed position and an open position to respectively prevent and permit delivery of fuel through the conduit means from the fuel pump into the combustion chamber and a pressure-sensing switch assembly connected in communication with a low pressure zone in the induction passage downstream of the throttle wherein sub-atmospheric pressure is created by reciprocation of the engine piston. This switch assembly is operable to selectively energize the solenoid-actuated valve to the open position when the pressure in the low pressure zone is below a predetermined level. The secondary fuel delivery system preferably is arranged to also serve as a priming fuel system.