1998 Johnson Evinrude "EC" 90, 115 SPL Service Manual, P/N 520209, Page 56Get this manual
Description of Outboard Fuel System
OJ The VRO pump assembly is combination mechanical fuel
The VRO pump incorporates circuit in the electrical module that warns the operator of "NO OIL" situation
and oil pumps and fueloil mixer powered by crankcase pressure and vacuum pulsesThe VRO pump injects the proper amount of oil into the fuel systemW
The 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 distribute and meter the fuel to the engineThey control the engine speed and power output by varying the intake charge densityTo react correctly to wide range of operating conditions, the carburetors have several discrete fuel mixing circuits