I picked up a Honda 50hp 4 stroke tiller a few months ago, about a 2001 or so. Water sure doesn't shoot out of the cooling indicator hose like it should. Took it apart yesterday, impeller didn't really look all that bad. Put a new one in anyway. Still not shooting water up like it should. I took the stat out of the top of the motor, water wasn't even going up that far, but stat was working. Doesn't seem to be any blockage that I'm aware of; I stuck a wire in the outlet where water comes out of the motor, nothing came out. There is a fitting there that apparently unscrews so you can clean it out, but I tried undoing it, and it would not move at all, so I didn't try any harder.
I'm going to take it apart again tomorrow, as I suspect when you slide the lower unit back on and the water intake meets the water pump housing, that isn't meeting up. The rubber gasket in there looked somewhat crushed when I took it apart. I'm going to take that rubber piece out and put it together, see what the gap is like and see if it still pumps water up.
This is kinda frustrating. Anything else, or anything specific I should be looking for?