I have a 1999 2500 24 valve.. Approx a year and a half ago I replaced the injection pump with a remaned one from thoroughbred diesel and a fass ddrp lift pump. About 3 weeks ago I fired up my truck after it was sitting for about 2 hours. I drove about a block and it started spitting and sputtering. I opened my water valve on the filter housing and air came out then fuel. It fired up and ran fine after that and was back to normal for a day or two. It then did the same thing again and I again opened the valve and air came out, it then fired up and ran fine. Now it's happening every time I go to drive it. There are no codes and my life pump pressure is superb at 15 idling and 13 WOT. It starts fine. I let it warm up. Listen for it to start running rough, turn it off, bleed the air, fire it up then drive it as long as I need with no problems. I also have just turned the key on and opened the valve before ever starting it and it blows fuel out with great pressure. So it only sucks air when it is running. I can not find any fuel leaks anywhere and my gas cap appears to be functioning properly ( judging by the air pressure when I open it).

Is your pump remote mounted on the frame rail or on the engine location? Where is your separator? It could even be in the pump if it's before the filter. Or as has been said, the top of the tank module. Steel lines? Rubbing somewhere or rusted? But it must be before the filter.

No it's a fass ddrp. So it's in the original location. I have the stock fuel filter. You know thinking about it, my gaskets on the pump could be leaking on the intake side. That would explain why it would be able to pump fuel with pressure and then as it ran dry air gets in the line until it is able to suck more fuel up.. Should I try buying a module from a wrecking yard and replacing it? Or too Risky because those may be cracked?

Although the DDRP can be mounted in the OEM location, they can also be relocated back nearer the tank as can the Carter OEM lift pump... I've had steel transmission & brake lines rust through on both my car & truck...

Eric, I have found it easier to lift the front of the box. You will need a 15mm socket to do it and a screwdriver to pull the three screws for the filler neck. The 15mm socket fits the six (short box) or eight (long box) bolts. Pull all the bolts EXCEPT the last two in the rear. Just loosen them and they will act as a hinge for the box. Pull the screws behind the fuel filler door and then lift the front of the box. Two guys can lift it or you can use another way to lift the box, but, MAKE SURE YOU BLOCK THE BOX UP!!! Then you can get to things and really look to see what is going on. You probably won't see anything until you pressurize the tank. Use a rag and a blow gun and it works pretty good. The module is real expensive (I was quoted $424 by one dealer) so you might want to explore alternative methods of repair (NAPA epoxy fuel tank repair comes to mind).

Awesome! Sounds easy to do that than drop the tank or pull the entire bed. Appreciate it!

So what happened? Did you find the problem?