I have a 2004.5 2500 with a Cummins 5.9l diesel. At 280,000 trouble-free miles, I replaced the engine mounted lift pump with a new Carter lift pump and a new in line clear fuel filter which was included and required to be installed by the seller. Afterwards, while priming the system with the new lift pump, the system functioned as expected for the first two cycles and then sounded like the fuel pump was straining. I checked for leaks and function of the new pump and everything appeared to be working fine but when I squeezed the fuel line below the lift pump after the cycle, there was a short but pretty good suction pulling the fuel back towards the tank. No DTCs were thrown. This morning I went out to recheck the pump and noticed that the clear filter was now only half full and when I lifted it off the rail, the filter drained completely back to the tank. I'm thinking that there is an intermittent obstruction in the tank, maybe at the in-tank filter and that this may be why the original lift pump died. I looked around the net and could not find a replacement for the filter on the in-tank module. So before I drop the fuel tank, would an obstruction of the in-tank filter or fuel line cause this time of scenario? If so, where can I find a replacement or can it be cleaned? Maybe compressed air through the line? What are the other possibilities? And now because of the suction on the lift pump and the sudden release of pressure back towards the tank, is my new lift pump toast now as well? I would appreciate any help and advice. I hope to avoid dropping the tank tomorrow as both the bed and tank are full and it will be a chore for me to do by myself and it there is an alternative, I'm willing. Thanks