1997 Johnson Evinrude "EU" 90, 105RW, 115, 150, 150W, 175 60 LV Service Manual, P/N 507268, Page 65Get this manual
Description of Fuel System
1The 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 several separate fuel mixing circuitsCarburetor calibration is controlled by slow speed adjustable needlean intermediate air bleed orificeand high speed fuel orifice 2Fuel enters the vapor separation chamber through the fuel filterThe chamber allows fuel vapor to separate from the liquid fuelThe vapor is removed from the chamber by the operation of the float valve and vapor pumpThe operation of the float valve is controlled by the amount of fuel in the chamberThe pump during start-up chamber provides liquid fuel to the and operation3The vapor pump is diaphragmdisplacement type, and is operated by changes in crankcase pressureThe vapor pump moves fuel vapor from the separation chamber to the air silencer
4The unit is combination mechanical fuel and oil pump, powered by crankcase pressure and vacuum pulses, which responds to various engine power settings by injecting the proper amount of oil into the fuel systempump incorporates circuit that warns the operator of The "NO OIL" situation5Mixture enrichment for cold starting is controlled by fuel primer solenoid When activated at the key switch, the solenoid pump output directly to the intake manifoldsdiverts some