1987-1993 Mercury Mariner Outboards 70/75/80/90/100/115HP 3 and 4-cylinder Factory Service Manual, Page 277Get this manual
Troubleshooting IMPORTANT: Determine if Electrical or Hydraulic problem existsHYDRAULIC SYSTEM TROUBLESHOOTING
IMPORTANT: Make one correction at timeCheck operation of trim system before proceeding to the next checkCONDITION OF TRIM SYSTEM ATrim motor runs; trim system does not move up or downBDoes not trim full downUp trim OKCDoes not trim full upDown trim OKDPartial or "Jerky" downupE"Thump" noise when shiftingFDoes not trim under loadGDoes not hold trim position under loadHTrail out when backing off from high speedILeaks down and does not hold trimJTrim motor working hard and trims slow up and downKTrims up very slowLStarts to trim up from full down position when "IN" trim button is depressedMTrim position will not hold in reversePROBLEM 1Low oil Level2Pump Assembly faulty3Tilt ram piston ball not seated (displaced, dirt, nickel seat)4Tilt ram piston O-ring leaking or cut5Manual release valve leaking (check condition of O-rings) (Valve not fully closed 6Lower check valve not seating in port side trim ram7Upper check valve not seating in port side trim ram8Check condition of battery9Replace motor assembly10Broken motorpump driveshaft2 PROBLEM 1, 2, 5, 10 2, 3, 1, 2, 3, 6, 8, 2, 5, 3, 2, 5, 8, 1, 2, 8, 3, 3, 4