It is not complicated. In the case of a no-start, I always suspect the level of fuel in the tank is below the point of fluid uptake (see broken hose, below). The best diagnostic by far for in-tank problems is simply to remove the hose from the back of the main pump and run it into a clear bottle, then crank for a couple of seconds. It should dump several fluid ounces in that time. But I assume you have pulled the in-tank (sending unit change)? No fuel means the pump is bad (rare) or the little black hose is broken (very common). That whole thing can be energized in hand to see if the pump is bad. Either at the pump terminals or the plug to the unit, separating a bad pump from a bad wire continuity. Why not replace the whole thing in the latter case? Or did I miss something.