The fuel pump should see battery voltage or ~12.0vdc. You can check the voltage drop in the wiring by putting one voltmeter lead on the battery (+) and the other lead on the fuel pump (+) terminal.... the reading is the amount of voltage drop.... you will have some, but it shouldn't be more than .5 volt or so.

There's no maintenance to perform on the fuel pressure regulator... it either works correctly or it doesn't. Unfortunately, without a mechanic's fuel pressure test kit, you can't check fuel pressure on our trucks.... and by the time you do the work to hook up a gauge port, you have the regulator exposed and might as well replace it.

Before you go to a lot of trouble, check the vacuum hose on the regulator and make sure it's not cracked or unplugged. The regulator is the round can on the rear of the fuel rail.... passenger side.

Frank