Outboard water pumps are located on top of the lower unit at the base of the driveshaft. The driveshaft turns a flexible neoprene impeller inside a specially-shaped housing to pump the water. The impeller is locked to turn with the driveshaft using a woodruff key or wedge. As the engine RPM increases, the water-pump pumps more water at a higher pressure. A small portion of the water pumped comes out as a small stream through the telltale at the side of the powerhead to let you know the pump is working.

This video shows a method of testing if the water pump is working.

There is no water coming out of the telltale

The telltale is the jet of water that comes out from the side of the outboard's powerhead. It is there to tell you whether your water pump is working on not.

Replacing the water pump impeller

It is important to replace the impeller and other wear items inside your outboard's water pump periodically.