If the fuel pump is replaced, any filter or screen should be inspected and replaced. This video is sponsored by Carter.
The earliest effort to improve fuel-pumps was to install a series of ballast resistors. This video is sponsored by Carter.
The first electric fuel pump circuits were very simple. The pump circuit usually involved a relay and fuse. The control side to the relay was typically wired to an ignition circuit or key switch. The control of the fuel pressure was performed with an analog regulator that could keep a static pressure and adjust for loads with a vacuum signal.
Andrew Markel explains what a P0191 code means, and how to ensure an accurate diagnosis.