Agreed, a bad plug wire has nothing to do w/ fluctuating fuel pressure. You are not talking about the standard fluctuation w/ vacuum built into the FPR are you? It's like 8psi. Obviously a cracked manifold gasket will cause a leak and give you a similar symptom, hopefully that was it! If switching between tanks doesn't fix it and you have an inline fuel pump mounted on the chassis under the drivers side of the cab, try swapping that out.. let us know how it does when its buttoned back up.

 

I'm not to good with what you guy's are talking about but could it also be perhaps where the fuel filter hooks into the line's it's not properly connected so it could be letting pressure out slowly?

 

Well I am as confused now as I was when I started. I changed the injectors and the truck does run a lot better but the ticking noise is still there. I mounted the gauge outside the truck so I could see it while driving and the fuel pump is working correctly. The ticking is still quite loud and you can still feel it in the the rail and lines, but the truck seems to run fine so Iam going to stop messing with it. The other 5.0 trucks I have heard do have some noise from the injectors, but nothing like mine. Oh well, drive it until it dies right! Thanks to everyone for there help and suggestions.

 

Valve spring, rocker, lifter, exhaust leak, shorting plug wire or simply regular sound from the injectors.. those are all the things it could be.. sorry you couldn't solve it but glad to hear its running fine.. just w/ a tick.