I have a 40hp merc that is not pumping water out when running. The tube that runs out the back is clean. I dropped the lower unit to inspect the impeller and it looked fine. I went ahead and replace it with an impeller kit and kept the old one as a backup. I ran the hose up through the tube that the impeller housing connects to and it flowed out the **** tube fine so I figured that there is nothing clogged. I remounted the lower unit with the new impeller and I have the same problem. I start the engine and no water comes out. I ran it long enough to start getting the solid alarm which I think is for the over temp. Maybe someone can confirm this or correct me on it. What else could cause the water to not flow?