How do you know when the fuel pump needs to be replaced in a 1989 Chevy Caprice?

Basically, the engine will not turn over. No fuel is getting to the engine. Disconnect fuel line at engine. Place line into container. 'Bump' engine and see if fuel is being delivered. If not, fuel pump. Another quick test is to get some gas and put a small amount directly in the injector/carb. Attempt to crank. If it briefly turns over and then off then fuel is not being delivered.