[Matttgo]

So me and my dad recently rebuild the 4.6 DOHC out of a Mach 1. Putting new everything including a Ford Performace high flow oil pump. We primed the system with the big sprayer pump method. Pumped almost 5 quarts and then topped it off thru the valve covers. Upon start up there was virtually no oil pressure for a good 5 seconds so we quickly shut it off and suspected a bad oil sending unit. As we were putting a new one on we realized that before the rebuild the oil pressure showed fine on the gauge so why would the unit go bad within the time of the rebuild, so instead went out to get a manual gauge and hooked it up to where the electric unit screws into. The needle did not budge. Getting desperate we finally undid unit and left the hole open and cranked the engine over with a non programmed key so it would just crank and not fire up, just seeing any signs the oil pump was working and hoping oil would squirt out of the hole. Not even a drop came out. At this point I don't know what to do or suspect. I'm guessing the oil pump if defective but it just seems like a really slim chance a brand new ford pump would not work like that. The pickup tube also had clearance as the oil pan went on smoothly without any force having to be applied. Getting ready to pull the **** front cover off and see if I can see anything that went wrong with the pump. Has anyone ever experienced this? I would love an answer or insite of what could be the source of my problem, if not the pump. Thanks guys