Throttle Control System

The dashpot diaphragm functions as a cranking opener. When the engine is at idle, intake manifold vacuum is applied on the dashpot diaphragm and pulls up the diaphragm rod, so that the throttle valve is in the idle position. During cranking with the starter, the spring in the dashpot diaphragm pushes the throttle valve open a certain amount for assisting engine starting.