A carburetor having a first valve to control the application of pressure pulses to a fuel metering assembly of the carburetor through a first flow path and a second valve which controls application of pressure pulses to the fuel metering assembly through at least a second flow path to provide an enriched fuel and air mixture to the engine to facilitate starting the engine and warming it up. The pressure pulses are preferably applied to a fuel metering diaphragm to actuate the diaphragm and cause a richer than normal fuel and air mixture to be delivered to the engine. Desirably, a maximum enrichment of the fuel and air mixture is obtained when both valves are open to facilitate starting the engine, and a lesser enrichment of the mixture may be obtained when only one valve is open to facilitate warming the engine up after it is initially started.