1997+ Mercury 35/40HP 2 Cylinder Outboards Service Manual PN 90-826148R2, Page 158Get this manual
Enrichener System (Electric Start Models) The enrichener system provides the engine with extra fuel charge for ease of starting cold engineThe system consists of an electrically operated enrichener valve which is connected by hose to the intake manifold
The enrichener system is pressurized by squeezing the fuel line primer bulb or by the fuel pump when the engine is being crankedWhen the ignition key is turned to the "on" position and pushed in (and held in), current is sent to the valve causing it to open, which allows pressurized fuel to pass thru hose to fitting on the intake manifoldWhen the key (or choke button) is released, the valve will return to the closed positionThe valve can be operated manually by pressing and holding button located at bottom of valveThe small hose connected to fitting at the base of the oil pump relieves excess crankcase pressure at the oil pump drive