1994 Johnson/Evinrude "ER" 9.9 thru 30 outboards Service Manual, Page 65Get this manual
Description of Fuel System
LJ operated
r;] 1The fuel pump is of the diaphragm-displacement type and is
by changes in crankcase pressureAlternately, suction and pressure in the crankcase are transmitted to the pump diaphragm
l=.J 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