How did you determine that the fuel injectors and fuel lines were not leaking? Just looking for a wet spot isn't conclusive. For example, a fuel injector that is stuck open will leak into the cylinder bore where you can't see it. Best way to find out if it is the pump or not is to hook up the pressure gauge, run the pressure test and while the pressure is still up take a set of vise grips and pinch the flexible return fuel line going into the tank. If memory serves, there are two flexible fuel lines coming out of the fuel tank. One is the send and one is the return. If you don't know which is which, just pinch them both off. If the pressure continues to go down with the lines pinched off then the leak is not the fuel pump check valve.
4.7L '03 Patriot Blue Durango SLT
Magnaflow Muffler w/ stock tubing