All of nothing pertained to the FP wiring. At any given time, it generally works enough to give you full potential or it's so screwed up that the pump won't run. It's not often where you have like 6 volts reaching a pump (which would lead to low pressure, through no fault of the pump necessarily).
I mentioned leaky injectors before. There are also obvious things that could lead to low pressure like an external fuel leak, crimped fuel line, clogged line or filter, contaminated sock, etc etc. Low pressure generally comes from things like a bad pump, restriction, FPR or a huge leak.
Good luck.