I changed lash adjusters and rocker arms(Ford Performance) on my 09 GT and now have no oil pressure. It was fine before I installed new parts. All electrical is hooked back up correctly and soaked the lash adjusters before installing. Car was only down for 2 days so I don't believe the oil pump would need to be primed, but I also did that. Any suggestions short of replacing oil pump? Hard to believe it's the pump.

 

if you still have the oil pressure sender unit disconnected, the PCM will show a low oil pressure warning
on the dash. this happened to me, and the solution was to attach a wire from the sender to engine ground.

after installing the sender, the warning light should go away.

 

Did your engine make any abnormal noises such as a loud tapping after you started it up? If it sounded normal and quiet, the engine did have oil pressure and the problem is either a bad gauge sending unit or the wiring connector is disconnected/broken.