for MOKI radial engines S 150, 180, 215, 250 and 250/7
At the side of the diaphragm fuel pump the fuel is pumped into the fuel line by the cyclical pressure and vacuum of the push rod pump.
On the side of metering champer is the relation of the pressure between dry side (pressure of Environment) and the pressure of the venturi (wet side of the diaphragm) responsible for the amount o fuel pass to the engine.
With an inlet control Lever System the inlet valve will be opened or closed.
Full open throttle -> low pressure in the venturi -> high differential pressure -> wide open control valve
Idle -> differential pressure very small -> control valve nearly closed
The control Lever System with the metering diaphragm sets the amount of fuel to every operating condition. Pressure fluctuations will be compensated.
The diaphragm will be worn over the years and should be changed every 10 years to achieve a perfect running behavior.
from stock !