tech ? non mopar

you know there is a fuel pressure regulator don't you? unless your fuel system runs deadhead to the injection rail you have a pressure regulator which comes back to tank. if working properly when you snap the throttle open the fuel pressure should increase marginally. the pressure regulator is actually controlled by manifold vacuum the higher the vacuum the lower.the fuel pressure? a simple test would be to cap your fuel return line at the rail. have your gauge hooked up and just turn your key on see what your fuel pressure rises to. if memory serves you should see between 75 and 80 pounds deadhead. I would hate to hear you had to change a tank unit pump and not need it.