2002 2500 auto had upgraded LiftPump(LP) to air dog raptor 3 years ago.
was driving to work one day and got on the highway and went to get up to speed i stomped it to the floor and it felt like the tire was spinning cause of rain on the road so i let off and then went to the floor with the peddle and just stuttering and bucking, was not able to go over 30 or 40 mph, got to the next exit and pulled into gas station thinking maybe plugged fuel filter which i changed 3 months ago and started it back up and died a short time later, didn't see LP pumping fuel into the housing. got it towed home and right away i tried the 2 wires on the LP and nothing, had the stock one and tested it and it worked so i ended up throwing that one back in, the Air Dog was under warranty luckly so i got a new one sent to me but i wasn't happy cause the plug was smashed even tho it was bubble wrapped. but after i put the stock pump in it ran good minus having to crack injectors once in a while, the morning i had it had dead pedal so i went around the block to come back home but all of the sudden all the power was there, drove fine for the 15 miles to work on the highway, did the same thing when i started it at work, idled for 10 min then went to leave and dead pedal again but then it was there after i shut it down and started it back up. but when i got the new LP put in it was running fine when i set the pressure and starting it and shutting it off and starting it back yup a couple times it started great, i went to go down the road i had all the power there then all the sudden truck died and would not want to start back up, my dad was with me so i started the walk back to the house then all of the sudden i heard him cranking it over and it started and had all the power there. so i jumped back in and went around the block and it was running great. got home and shut it off and it wouldn't start back up so i tried injectors quick.

current condition is a no start, when i look at fuel gauge it will register pressure every other time the LP is running which is weird, it will only try to start when the gauge is registering pressure. i do have new sealing washers ordered for banjo bolts and a new overflow valve coming also. will try a new FP Gauge this weekend. but it just stumps me, i did have the dreaded CEL code for the vp44 but i did run out of fuel a couple years ago which is what set that off, just never erased it. i did replace fuel filter and o-ring on the cap .

anyone have anything else to check? or any input im thinking about replacing the MAP sensor and debating on the throttle Position sensor

 

So is the LP running every time you try to start it and just not registering pressure or is it only running intermittently?

Those pumps will start and run with only two wires (pins 6 & 7) which removes all other factors from the equation, other than of course fuel.

 

I hear it running every time bit not registering pressure every time

 

well I did some more tests like cleaning the map sensor a little and checked a couple other things and also put the stock L.P. back in and I'm guessing the vp44 is toast. it won't build pressure anymore right now. I did replace the overflow valve which was shot. it did want to start up after turning over for about 45 sec. but then died. I was searching around and found this thread and pretty much the symptoms I have are stated for the vp44.

https://www.dieselbombers.com/98-5-02-cummins-24v-5-9l-vp-44-tech-talk/4940-diagnose-vp44-fuel-system.html

 

turns out it was the fuel line from the tank had rusted and was leaking. got fixed and now I thing just the throttle position sensor is bad cause I get dead pedal when I start from cold, but when I recalibrate it it a good

 

Nice, good to get off lucky once in a while......