Oil pump won't prime

[sickass50]

I'm finishing up a new build w/ a melling oil pump w/ billet gears and I can't get the motor to prime. I've spun the engine with the starter for a minute to minute and a half and am not getting any oil to the filter. Is there any way to prime the system without turning the motor over? The pump is new, the o-ring on the pickup is new. I put on a Moroso 8 qt. pan and put in 8 qts. and the dipstick reads a little low so i was going to add another half quart or so to bring it up on the dipstick a little, although i don't think that is the issue. I put together the motor myself and installed the pump, everything lined up and i don't see how it could be installed wrong. Its pretty self explanatory. Any help is appreciated, I'm really not looking forward to pulling it apart to get to the oil pump.

 

[oldmodman]

I primed a new motor by filling up a garden sprayer (2 gallon) with oil and pumping it in the hole where the oil pressure sender goes. I pumped all 8 quarts into the engine, drained the oil back out, filtered it, and pumped it back through a second time. Drained it again and refilled with fresh oil then started it (after reinstalling the oil pressure sender). Had oil pressure instantly. And since this was just helping out a friend that had installed a shortblock from Ford I have no idea how the stock oil pump was prepared. But if I was building the engine I would have also packed the new oil pump with grease before installing it.

 

[Quick Strike]

I had the same issue here using the same pump, but I have the canton pan. I wanted to see oil pressure and make sure the cam tensioners/valve train were working propperly before installing the motor, but I also had no pressure after cranking for 30 seconds. So, I used a garden sprayer (as above) to pump oil into the head from the oil pressure sender port. I had oil in the heads, but still no pressure at the gage. Then I attached a hose over the threads for the filter and used the sprayer to pump oil back to/through the pump. I filled the filter and reattached it. Now I had 20# of pressure just cranking and lots of oil on the floor since the valve covers were off. I was happy to clean it up!

I think the engine cranks too slow to prime without any oil already in the system. Many guys start with the oil pump dry with no priming issues. The engine is spinning much faster when started and this creates a larger vacuum. Anyway, I have over 500 miles on it now, and never had another oil pressure issue once primed. The sprayer was $15 at my local hardware store and the fittings (once figured out) were just a few bucks.