Fuel Enrichment Pressure Switch

Fig. 17 Fuel Booster Pressure Switch:

When the engine is operating at a constant speed, the pressure is the same on either side of the diaphragm in the pressure switch, Fig 17. When the engine is accelerated, the pressure in the valve increases, but because there is a restricted orifice between the upper and lower chamber, the diaphragm moves down and closes the contacts of the switch. When the pressure equalizes, the diaphragm moves upward, thereby opening the contact switches.