1987-1993 Mercury Mariner Outboards 70/75/80/90/100/115HP 3 and 4-cylinder Factory Service Manual, Page 288Get this manual
11Run trim "UP"The minimum pressure should be 1300 P.S.I(91 kgcm2)12Run trim "DOWN" to release pressure and remove spare tilt pin or bolts and nuts13Tilt outboard full "UP" and engage tilt lock lever14Slowly remove "Fill" plug to bleed pressure15Open Manual Release Valve to turns to bleed any remaining pressure16Remove test gauge hose and adapter, and install allen plug 2Install components
NOTE: If pressure is less than 1300 PSI (91 kgcm2), troubleshoot system per instructions on page 6B-7
"DOWN" Pressure Check
1Repeat steps through from preceding "UP" pressure check, removing allen plug as shown51360
aAdapter Fitting (22-11243)Hose (route hose so it will not be pinched when outboard is trimmed "DOWN")Test Gauge AssemblyValveValveHose (not used for this test)