Accelerator Pump System
Acceleration from idle to higher engine RPM does not supply enough vacuum to draw sufficient fuel from discharge arm into mixing chamber. As throttle valve is opened further, vacuum decreases causing a lean condition. To prevent a flat spot during acceleration, the accelerator pump injects an additional amount of fuel into mixing chamber through injection tube. Accelerator pump diaphragm is actuated by throttle valve lever pushing on diaphragm lever through connecting rod. Diaphragm draws fuel from float bowl through check ball valve and forces fuel past injection tube check ball valve through injection tube and into mixing chamber. As idle RPM increases to a higher range, vacuum will draw fuel through injection tube out of float blow through accelerator pump.