1989 Johnson Evinrude "CE" Colt/Junior thru 8 Service Manual, P/N 507753, Page 66Get this manual
Description of System
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 consumed It 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 either choke or manual primer