1973 Evinrude Norseman 40 HP Service Manual, Page 16Get this manual
DESCRIPTION FUEL FLOW The fuel system consists of fuel tank, fuel pump, and carburetorThe fuel tank is non-pressurized, suction operatedA diaphragm-displacement type fuel pump on the motor draws fuel from the tank and furnishes it to the carburetor through fuel filterCARBURETOR The carburetor is single-barrel, float feed typeThe high-speed jet and low-speed jet are adjustableThe carburetor has manual chokeThrottle linkage is synchronized with the magneto by cam on the magneto armature plateSee Figure 3-1
The carburetor throat is frequently called the "barrel Carburetors with Single, double, or four barrels have individual metering jets, needle valves, throttle and choke plates for each barrelThe two barrel carburetor is fed by single float and chamber while the four barrel model has separate float valve and chamber for each barrelINDUCED LOW PRESSURE VENTURI