2003 Ford Mustang FUEL PUMP

The pump is supposed to stop running until the Engine Computer sees engine rotation. That is the safety feature to prevent pumping fuel onto the ground if a fuel line gets ruptured in a crash. The pump will run while you're cranking the engine.

By "same thing" do you mean it runs continuously but you get just a dribble of gas? I don't know if your pump is the same as older ones but in some cases it pumps fuel into a bowl, then pumps from that bowl to the engine. If you have the assembly out of the tank and you just set the pickup screen in some gas, it won't pump any gas if that bowl is empty.

Also, before you buy the new one, Ford had a problem on some models where they had a rubber hose connecting the pickup screen to the pump. That hose would dry rot and leak. Air would get sucked up instead of gas. The clue was the car would run fine until the level in the tank dropped enough to expose that leak. As I recall, that occurred at about 1/4 tank.

Couple of observations. If you hear the pump run for one second when you turn on the ignition switch we know it's working. If not, don't overlook a bad ground. Typically there is a ground wire in the connector for the pump motor but it's possible they just use the metal gas tank against the metal tank straps or car body.

Check for spark. If it is missing the fuel pump will not run during engine cranking. That's a safety feature to stop the pump if a fuel line gets ruptured in a crash. The place to start for that is by checking the diagnostic fault codes. They won't say to replace any parts. They just indicate the circuit or system that needs further diagnosis.

Ya gotta love computers. Too bad anti-theft systems keep more owners out of their cars than the thefts they prevent. Happy to hear yours is solved.