do a search ,there is plenty of info about fuel pumps and test .
To answer your question ,the fuel system has a return line so I assume that when the car is running the pump runs all the time together with the fuel pressure regulator.
When my pump went I put 12 volts directly to the pump and got nothing . that told me that the pump was no good. Don't go cheap , buy the correct one if you need it.They should last between 150 - 200,000 miles.
You could also hook up a fuel pressure guage at the pump and crank the motor to see what you have for pressure . You should have around 43.5 psi.
GOOD LUCK
