Mercury Mariner V-250 V-275 Outboard Service Shop Manual 1990, Page 312Get this manual
4Secure co nnector retainers together using suppl ied sta-straps Bleeding Power Trim System
IMPORTANT; "FiIINenf" screw (a) must be backed out 1-12 turns to vent the pump reservoir1Makesurethat manual lilt knob (b) is turned full "i n" (clockwise, finger-tight on ly) andFiIIlVent" screw (a) is backed out 1- 12 turnsNOTE: For tri pump to electrically operate, the engine harness connector must be connected to eng ine and engine and trim pump battery leads connected to battery2Activate theTra iler" switch and trim outboard to full "up" positionIf outboard stops part-way-up (lack of oil)refill pump to "addline (not the full tine) on dipstick Continue this procedure until ou tboard raises to full "up" position