[Sean Marconette]

Billy,
I just sold my 2002 3500 last year, a couple differences in my truck it was a 6 speed and had 4.11 gears and was a 2wd, same engine as yours. I had it for 10 years and pulled a heavy 48 ft LQ trailer. One of the first things I installed was an electric fuel pump to increase the lift pump pressure to 24 PSI, and installed a Edge Juice with Attitude tuner and a non restricted exhaust. The tuner in towing mode was like a different truck, and would pull hills without issue. Everything else was bone stock including the air filter. I bought it with 49K and sold it with 119K. Fuel mileage pulling the trailer was 12 MPG, no trailer 19 MPG.

Your lift pump pressure is too low, and if the VP is not damaged it could be. If the turbo is in good shape, I would invest the money in a tuner, before hard parts other than a pump to get the VP happy. I ran a Holley blue pump as the lift pump and adjusted the spring to increase the pressure. I replaced the Holley pump 2 times as it would start leaking fuel at the seal, but worked without issue and served the purpose to get fuel to to the VP.

Sean