lacking fuel delivery.

[jeremy cato]

I have a fuel delivery problem. I recently put a freeze plug in my 1996 Ranger splash 4.0L V6. I changed the heads and put other heads on it. I also changed the fuel pump and the fuel filter but now I have to prime the fuel rail for it to start running have ass decent to get it to stay running. I know it isn't a head gaskets because there isn't any water in the oil. Can someone shine some light on a potential problem or point me in the right direction or in any direction? It'll crank but then dies, but if i squirt gas in the breather it will run and then it will prime and starts running good. if i turn it back off and crank it again, I have to repeat the process all over again. The motor in it now came out of a 1998 XL ranger with the same OHV 4.0L V6 so the heads off of a 1996 OHV 4.0 fit perefect but I'm having fuel problems.
Help!

 

[alwaysFlOoReD]

Put a pressure gauge on it. I can't remember if 96 is 40psi or 60. Bit regardless, it should be holding pressure for months. If not that means a leak, probably internal.