Ok, I think I understand what your saying now. So basicly its like a siphon or suction effect, where the higher vaccume of the engine at low load is actually kinda helping to suck the fuel out of the injector, then at low/no vaccume, the fuel is simply being pushed out the injector by the fuel pressure alone. So at high vac, its sucking the fuel out, so less pressure is given so they dont flow as much, then low/no vac, pressure goes up for more flow.
Do I have that more or less right?