On top of the pump there are two electrical connections -- one is ground and the other is hot -- inside is a solenoid that actuates the throttle valve. You can remove the "hot" wire and touch the post where it came from, to hear the solenoid click.
There is a lever with a spring on the solenoid that causes the throttle valve to close when current is off. With todays craptastic fuel quality, -- … well anyways it should be clean and shiny inside the cover.
Some of the pumps had a rubber flex plate inside that would break up and particles of it would get into the linkages and return line orifice. If your feeling especially inclined, you could remove the screws holding the top cover and inspect the solenoid for junk. -- if you do -- don't over tighten the screws and strip them out.