1992 Johnson Evinrude "EN" 9.9 thru 30 Service Manual, P/N 508142, Page 61Get this manual
Description of Fuel System
t!J operated by changes in crankcase pressureAlternately, suction and pressure in the crankcase are transmitted to the pump diaphragmf21 2The carburetor meters and distributes the fuel 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 circuits