Yamaha 40 horse outboard,changed impeller but it does not pump water

I recently got my step dads boat when he passed away. it has a 40 horse yamaha that did not pump water. I bought a new impeller and installed it,and it still does not pump water. Any advice would be greatly appreciated

1. When you say it doesn't pump, do you mean it is over heating or are you relying on water coming from the pee hole?
Those pee holes clog real easy with insects and pushing a piece of stiff wire or metal cloths hanger in it with engine running in/on water will clear out the hole.

2. Was the impeller you removed missing any pieces? If so, a piece may have lodged into the water tube?

Otherwise:

You may need to remove the lower unit, and while lowering it, look up where the water pump cover is to see if the water tube was in the top of the water pump casing. Some engines are difficult to keep the tube aligned when pushing the lower unit up. Sometimes people don't notice the tube isn't going into the pump.