1987-1993 Mercury Mariner Outboards 70/75/80/90/100/115HP 3 and 4-cylinder Factory Service Manual, Page 304Get this manual
5Tighten trim sender screws
aTrim SenderConnect with screw and hex nut (coat with liquid neoprene)cRubber Sleeve (Slide over connection)
Trim Indicator Gauge Needle Adjustment
1Turn ignition key to "RUN" position2Tilt outboard to full "IN" positionNeedle of trim indicator gauge should be in full "IN" position3If not, tilt outboard to full "OUT" position to gain access to trim sender and engage tilt lock lever4Loosen trim sender screws and reposition trim sendera 22744 Trim Sender Screws, loosen to rotate sender Turn sender counterclockwise to raise needle readingTurn sender clockwise to lower needle readingTilt Lock Lever