Re: 1994 - 4 horsepower evinrude
Check/replace the pump impeller but while the lower unit is off check that you can get a flow of water through the engine from a hose connected to the bottom of the water tube. If you cannot it may be due to blocked water passages or it could just be that corrosion around the grommet at the top of the water tube is squeezing it closed over the top of the tube.
The lower unit is held by 2 screws, I think, maybe 3.
If you have a long shaft model remove the leg extension with the gearcase, clean up the drive shaft and then remove the extension from the gearcase. If you try to remove the gearcase leaving the extension on the leg you will probably damage the water pump!
Do not enlarge the pee hole if you do it may affect the water distribution within the engine. It is only a telltale.
You will find the engine parts diagrams on the brp website very useful.
http://epc.brp.com/default.aspx?brands=ej&lang=E