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.

 

[jeremy cato]

what do you mean by internal? oh, and is that test preformed on the fuel rail?

 

[alwaysFlOoReD]

what do you mean by internal? oh, and is that test preformed on the fuel rail?

Most of what I know is on older stuff. But maybe someone else will correct me if I make a mistake...
I think your in tank pump has an internal check valve, which if it isn't working will allow the pressure to disappear.

Try turning the key to run several times. But don't start the engine. Each time you turn the key the pump will up the pressure by ~10psi. If the engine starts fairly easily after turning the key a bunch of times, then you know there is a leak. You can research how your trucks fuel system is designed and fix it, or just keep doing the key turn trick.