That would work as well

 

am i low on fuel or something? cuz when im on a hill thats when my fuel pressure drops..

 

Well when there is a load on the truck it will drop some. How much fuel is in the tank? if its low fill it up and see if it changes. You could have a 1/4 tank issue.

 

i have a 98 5.9 24 valve with replacement ddrp lift pump was running fine
now after about mile or two fuel pressure goes from 20lbs to zero
i have to pull over and shut truck off and let sit five min then pressure goes up good for another two miles so on

sometimes if driving i take my foot off pedal pressure goes back up

what can do this ecm ???

 

You have a restriction in your fuel system. Either your lift pump is not pulling the fuel from the tank or your fuel filter is clogged, or maybe you have some solid particulate in your tank that is being sucked in or around the fuel pick up. After letting it sit, it falls away and fuel pressure is restored. We had this on a big Peterbilt at work where someone dropped a rag into the tank. As common as the lift pump failures are on these, I would suspect that but I have seen fuel filters do this as well. Personally, I would replace the fuel filter first. I have seen many problems from aftermarket filters that get a little dirty and stop flowing. I personally also only recommend Fleet Guard or Mopar filters. Fleet Guard makes the filters for Mopar diesels. If you buy a Mopar, you are buying a Fleetguard.

Good Luck

 

okay so now i have installed a 100gph raptor frrp. the fuel pressure it 25psi when i bump the starter. i start the truck and after about a min. the fuel pressure drops and does not pick back up.

 

Have you checked or replaced the pressure regulator? It is built in to the return line Banjo bolt.