It takes a pretty significant amount of cranking to get the HPOP to build enough pressure to start.... Also like the other fellas have said a fuel pressure gauge will be required. When I did mine I jumped my fuel pump and let it build up pressure on the system to purge some air. I can hear a difference in the regulator when the fuel reaches it.

 

I have a regulator on and am at 65 psi. The fuel isn't coming out of the return though at the bottom of the regulator. I'll try jumping the pump tomorrow

 

Maybe you damaged the regulator when it was hooked up wrong? Here is a picture of mine when it was installed in the truck. Same as yours, correct .. Bar None - FuelLab brand.? The adjustment screw is about 1/2 inch high from the top of the regulator which gave me 60 PSI. Hope this helps.

 

Yes, regulator is the same. About the same height on the screw. I'm reading 65 psi. Pulled the regulator apart, all internals are fine. Cleaned it out, put it back together. Still no fuel in the return. I'm at work now but will hook up the fuel pump when I get off

 

I can't envision having 65PSI and nothing coming out the return line. You do have the ball shutoff valve on pre filter turned OFF? Stupid question I know but easy to forget. Did this fuel system work before swapping engines? Did you get the wiring issue resolved? Just thinking out loud.

 

Primed the fuel system. Jumped the fuel pump. Still no start.

 

Still nothing from return line? Still 65 PSI? My previous post, is the shut off valve turned on? I can assure you there should be a lot of fuel returning to the tank and it's under pressure due to the small 5/16 line.

 

Yup, still 65 psi, still no fuel in the return. I have it on. And yeah the fuel system worked before the swap. I have no clue what's going on. Checked all of my fuses and they're all fine.