99 Ram 3500 diesel. Starter issues. Starting some of the time but less and less often. Hitting solenoid with hammer has no effect. When I changed the high pressure pump last year I also changed the lift pump to a larger aftermarket raptor pump. At the same time I added a LED light to indicate if the lift pump was getting power. Currently, 95% of time, when I turn key I get a loud click from the starter but the lift pump does not turn on. After 20+ clicks fuel pump will come on temporarily and pressurize system. After several more cranks lift pump will shut back off and indicate that it is no longer receiving power. Occasionally the engine will begin to turn over but will cut back out in mid crank.
Does starter solenoid control the relay to the fuel pump? Any ideas?

 

Disclaimer: Diesel is not my strong suit.......

That said..... digging thru the wiring diagrams, it looks for all the world like the lift pump is powered directly thru the ECM...... which strikes me as kinda strange..... seems like a pump would have a pretty good current draw for the ECM to deal with.... Now, what criteria the ECM uses to decide whether to power the lift pump or not.... is another question entirely.

Might get better answers from the Diesel section here, or, over on the Cummins Forums.