Over the past month Ive developed fuel delivery issues. First crank of the day has no issue. As I drive it around town the harder it is to start. Today I ran it at 70mph and it died. Got it to start again after multiple long cranks and limped it home. New filters 1 month ago and changed them today thinking it was a filter issue. That does not seem to be the issue. I will add that the normal sounds of the system priming seem to be absent.
I thought if a pump goes it just goes. So I have a couple of questions. (1)How many pumps are in the system? The dealer has told me that it could have two. One on the rail that I know about and one in the tank. (2) What electronics are tied to the system? Im guessing that its something simple, but not sure. Any advice would be appreciated. I hate throwing money at it, not knowing for sure.
What is the fuel pressure? There is a test port on the fuel filter housing on top of the engine.
There is just one pump, located under the truck, below the drivers side seat area, hanging on the frame rail. No pump in the tank for any 6.0, so I don't know why your dealer didn't know that. There is nothing electronic in the tank besides the fuel level sender.
The electronics are: Power and ground to the pump and a couple wires for the "water in fuel" sensor.
My suggestion is to test the fuel pressure, if you are convinced it is a fuel related issue. If you have not installed the updated "blue" fuel pressure regulator spring, now would be a good time to do it.
Next, if your issue is only present while the engine is hot, that points more towards an HPO system leak than a fuel pressure problem. You would have to get an electronic gauge set on there and monitor the IPR% and the ICP psi to help determine if that is the case. Those will just tell you IF you have a HPO system leak, and not tell you what is leaking in the system. You would have to pressure test the system to determine which component is leaking.
As far as the HPOP, the pump in the 05-up trucks is a much better piece than in previous years. This isn;t to say that they don't fail, but that a failure is much more unlikely than previous years. However, the fitting that attaches the HPOP to the HPO system in the 05-up trucks is an STC fitting. This fitting will fail in every engine, it is just a matter of when. The replacement fitting is a straight fitting, which will not fail.