Well, fuel pumps pump fuel. Its kinda their thing.
So, if the pump is running, and you take the line loose at the injectors and have no fuel, then it can only be a few things.
No gas in the tank for the pump to pump.
Clogged fuel filter, or crimped or stopped up line.
Pump installed wrong, but for the life of me I can't figure out a way to do that so it won't pump.........Upside down maybe??
Well, I guess you could somehow hook the lines up wrong. Maybe hook the vent line to the output and be filling up the charcoal canister.......
Bad new pump.
That could be an actual defective pump, or the line inside has come loose.