1991 Johnson/Evinrude Models "EI" 40 thru 55 Service Manual, Page 62Get this manual
Description of Fuel 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 diaphragm
The carburetors meter and distribute the fuel consumedThey control engine speed and power output by varying the intake charge densityTo react correctly to wide range of operating conditions, the carburetors have multiple fuel mixing circuits
f31 3The unit is combination mechanical fuel and oil pump, powered by crankcase pressure and vacuum pulses, which responds to various engine power settin2s by injecting the proper amount of oil into the fuel systemunits incorporate circuit that warns the operator of "no oil" situationf51 4Mixture enrichment for cold starting is controlled by either manual primer (rope and TE models) or fuel primer solenoid (remote control models)6720