How can you tell if you have a bad fuel pump?

 

Most common ways to judge a pump is to measure the fuel pressure at the fuel rail.
At first igniton move to run, for starting, the pump is run for about 1 second +/- to begin rail pressure.
Repeated actions will boost the pressure to max allowed by the regulator of about 40 psi.
At cranking, the PCM restarts the pump again and ensures the rails are fully presserized as long as the motor is running.
After motor shut down, the rail pressure should keep at it's level for a lengthy number of minutes afterward.
If not, suspect one or more of the following, pump check valve is not holding, regulator is faulty or injectors are leaking the rails down and possibly flooding one or more cylinders.
Knowing these things should enable you to do testing and make a logic decision as to the condition of the pump/fuel system by the test results you get.
Otherwise, a pump volume vs time test can be done but is a pain to do.
Good luck.