Just got done replacing my oil pump with a melling high volume oil pump, went to check the pressure with a mechanical gauge and there's zero pressure whatsoever. Took the pump out and verified that it worked and the pressure relief valve wasn't stuck open, re installed it and cranked the engine with the oil filter off, no oil flow whatsoever. I haven't inspected the oil pickup screen but from what Ive observed, the pump is working, there's no clogs in the oil system, the pump is installed correctly, and there's no flow whatsoever. Kinda at my wits end with this thing anything helps.

It's a 2010 5.4 3v SOHC v8 (with the vvt phasers)