How do you install a water pump on a 4.5HP Johnson outboard motor?

To install a water pump on a 4.5HP Johnson outboard motor, first, remove the lower unit by disconnecting the bolts and shifting linkage. Next, take off the water pump cover and remove the old impeller and gasket. Install the new impeller, ensuring it’s oriented correctly, and place a new gasket before reassembling the water pump cover. Finally, reattach the lower unit and ensure all connections are secure.