Mercury Mariner V-250 V-275 Outboard Service Shop Manual 1990, Page 278Get this manual
3Activate the "Trailer" circu it and trim engine to full "up" position If engine stops part-way (lack of oil)refill pump to "addline (not the fu ll line) on dipstickContinue this procedure until engine raises to full "up" position 4Activate theDown" circu it and trim engi ne to fu ll "downposition If pump sounds like it is ru nning freeand the engine does not trim down, fill pump with oil to "add" line on dipstick5Bleed any remaining air from the trim system by trimming eng ine several times th ru entire trailering rangeEach time, engi ne is trimmed to fu ll "down" positionfill pump with oil to "full" li ne on dipstick 6Reinstall "FiIlN ent" screwTurn screw in until seated then back out 1-1 2turns to vent the pump reservoir7Check entire trim system for leaks WIRING CONNECTIONS Refer to wiring diagram in Section 2