Mercury Mariner V-250 V-275 Outboard Service Shop Manual 1990, Page 282Get this manual
If BOTH "Up" pressure andDown" pressure readings are lowreplace pumpReferto "Hydraulic Repair"see Table of ContentsOperate Power Trim system to see if problem has been corrected If problem has not been corrected, replace adaptorReferto "Hyd rauli Repair", see Table of ContentsIf BOTH "Up" pressure and "Downpressure readings are zero, check to see if coupling between the armature