1998 Johnson Evinrude "EC" 2 thru 8 Service Manual, P/N 520202, Page 55Get this manual
Description of Fuel System 2,2.3,3.3
1The fuel system consists of fuel tank mounted on the powerhead, fuel filter and shut-off valve assembly, and carburetorFuel flows, gravity-fed, from the fuel tank to the carburetor
1The fuel pump is of the diaphragm-displacement type and is operated by changes in crankcase pressureAlternately, suction and pressure in the crankcase are transmitted to the pump diaphragm2The carburetor meters and distributes the fuel to be consumedIt controls engine speed and power output by varying the intake charge densityTo react correctly to wide range of operating conditions, the carburetor has multiple fuel mixing circuits3Mixture enrichment for cold starting is controlled by choke