Mercury Mariner Outboard 225 3 Litre Service Manual 1994, Page 198Get this manual
" UP" Pressure Check IMPORTANT: Insure battery is fully charged before performing tests1Tilt outboard to full position and engage tilt lock Ie Upft ver2Slowly remove voirplug to bleed pressure from reser
5Install components
3Turn Manual Release Valve to turns (counterclock wise) to bleed any remaining pressure4Remove allen plug51374 51353
Allen Plug