a fuel supply apparatus for an internal combustion engine in which fuel is supplied to the air induction tube in proportion to the aspirated air flow rate . a fuel metering valve , which may be electromagnetically actuated on the basis of engine rpm and other variables , is connected to the induction tube , possibly into the bypass channel of a carburetor to provide fine fuel control . between the fuel metering valve and the induction tube there is disposed a pneumatic valve assembly including an equal pressure valve , the pressure chamber of which controls the fuel flow and the control chamber of which is coupled to the pressure chamber of a further , differentially - biased pressure control valve connected to downstream portions of the induction tube . the differential pressure valve maintains the control pressure in the equal pressure valve .