just an observation from working on these things for years... In 05 Dodge put the lift pump in the tank. I was thinking, "great....now I'm going to have to drop the tank when these pos things fail".....but they didn't, and it was about that time that the "retrofit kits" came out which covered the trucks back to 98.5. With the common rail trucks (03 up) I've never seen a related part failure when the lift pump failed....the truck simply quit running, and "if" I've replaced five of them over the years I'd be surprised.

On the 98.5 to 02 VP44 equipped trucks.....different deal. It's pretty common knowledge that if you starve that pump you can possibly damage it. I have an 01, and my first injection pump died at 77K. This was with the factory installed lift pump that was still putting out 12-14 psi at idle, drops to maybe 3 at the hardest of pulls. I still run a stock lift pump to this day. I swapped the original out in 08 as it was starting to leak which later I found a tsb from Cummins for replacing the top diaphragm (gasket) due to ULSD. Bought a gask from a Cummins dealer and it's now my spare pump. I did procure a in tank pump when my truck was still under warranty, but it's still in the box. IIRC most of the time the idle psi with those was 9-11 and I don't ever remember seeing them drop to zero, close, but never zero. I'm not a believer of having "14psi to the VP at all times to save it".... I've replaced injection pumps with about every fuel system under the sun. FASS does back their product up "IF" it's installed correctly, but you're looking at alot of down time as you have to have the pump removed and then sent to them for inspection. Most I've replaced were trucks from the north that had road salt corrosion and the motors failed, thus my disliking of them.