1987-1993 Mercury Mariner Outboards 70/75/80/90/100/115HP 3 and 4-cylinder Factory Service Manual, Page 111Get this manual
Enrichener System Description for Three Cylinder Engines
Fuel flows from top carburetor float bowl to fuel enrichment valveValve is electrically opened when key is turned to the "ON" position and pushed in (and held in)Fuel is supplied to engine through fittings located in the top, middle, and bottom carburetorsValve returns to the closed position when key (or choke button) is releasedValve can be operated manually by PRESSING and HOLDING button located at bottom of valve
Description for Four Cylinder Engines
Enrichener valve receives fuel from T-fitting between #1 and #2 carburetorsValve is electrically opened when ignition key is turned to the "ON" position and pushed in (and held in)Fuel is dispensed to T-fittings on intake manifold of cylinders #2 and #4Internal passages route fuel from cylinders #2 and #4 to cylinders #1 and #3Valve returns to the closed position when key (or choke button) is releasedValve can be operated manually by PRESSING and HOLDING button located on top of valve