Water pump problems

!987 8 HP. Have changed inpeller and gasket,still no water out telltale. Checked thermostat, OK. On this engine, will water come out the telltale with thermo closed? What other components should I look at for lack of water. I have blown through telltale and water pickups and checked for obstructions.

[boats.net]

If the engine is overheating then there is still a problem with water pump or a blockage in water passages. If engine is not overheating then may be a blockage in telltale.