raw water pump

OK, I replaced the impeller, thermostat(there was not one there) and the hose running from the transmission cooler to the raw water pump on my 1978 Ski Nautique.I put the boat in the water and it ran hot. I disconnected the hose coming out of the raw water pump at the thermstat housing and there was no water coming out. I pulled the boat out of the water and nooked up a water hose to the system at the hose attached to the bottom at the fresh water entry port. The boat ran at 150 for about 15 minutes and everything seemed fine. The water came out the exhaust( more,on the left than the right) and the engine never overheated. I put the boat back in the water and it overheated. Iwent through the same routine and no water came out when I disconnected the hose ccoming out of the pump. What is wrong? Is the pump on upside down? The pump felt hot so I replaced the impeller (again)and am ready to try again. The pump was installed with the entrance and exit ports on the top. The "Shwewood" name was on top so I thought it would be right but it did not draw water. Please help.

Stevie;
     I had a similar problem with my Sherwood pump. Mine is a dual cavity, double impeller pump. There are 2 bronze cams,( kinda like half moons with 2 slits in them) in the bottom of the suction portion of the pump cavity, that bends the impeller blades over, and creates suction. Since mine is a 66 model, these cams become worn over time. I replaced mine and all was well. Also on my pump body "IN" and "OUT" are cast into the pump body so you can't get mixed up, or upside down. Just remember, the cams are on the bottom, this is the suction side. A impeller pump dosen't care which rotation the engine is. When you put the pump together, use some dishwashing liquid soap. It helps to lube the impeller. I try to use some every time I take mine out.

My pump was on upside down. Problem solved.