First cold day in Georgia where I tried to start up the truck without any luck. The engine stumbled along and along, so close to fully firing up it almost made me cry. After starting, with the key in the "run" position, the lift pump continued to run for around 30 seconds. I could tell it was running by the clicking sound it made - not what I would define as a "purr," closer to the "loud clacking sound" but not sure how loud the noise should be. Is any noise considered bad?

About a month ago I tested the lift pump on the bench. With the inlet submerged in a glass jar of fuel, it pumped it through the outlet when energized. I've powered the unit on the chassis with +12V and gotten fuel through the T-valve. Also replaced the fuel filter a few weeks back and bled it through.

Appreciate any advice and thoughts!

Open the T-valve while the motor is running. If you truck dies the lift pump is bad. You could also put a fuel pressure gauge there check that reading. What are the condition of your glow plugs?

After substantial testing, glow plugs are officially kaput. Should have thought of them sooner!

At least it was still warm enough that you could start your truck and its best to find that out now before it got even colder out.