Before I get beat up on here,let me clarify.
The fuel pump actually pulses.When fuel is not flowing to the injectors,there is back pressure in the line and the fuel pump will shut down. Same thing with air in the line...too much back pressure and the fuel pump shuts down until the pressure is released.
It's the job of the fuel pressure regulator and the fuel return line to keep the rail at a constant pressure under different demands.
89 yj w/ mopar mpi and 4.0 head.94 ax-15 tranny and t-case, more mods comin.