Have a 2001 Freightliner MT55 with a 5.9 cummins.
Here's my issue - Will start first thing in morning, runs 10 - 20 seconds, coughs a couple times and stalls. It wil restart after lots of cranking like it has to get primed again and once it does start - it runs fine. If I shut it off for short periods it will start back up. After being shut off an hour or so(seems like it takes less time lately) it does the same thing as in the morning as if it is losing its prime. Found some external fuel leaks(return line fittings) and re-sealed them.
Problem still exists.
Can feel lift pump vibration as if its working(external lift pump - believe it to be o.e.m.).
Can fuel drain back through lift pump or are they supposed to be like a check valve?
Had a new vp44 put on last year and once the truck does start, it runs fine.
Read somewhere that injector connector/crossover tubes have orings at injector that crack and leak.
Would that cause this? Seems as though there is fuel at the injectors initially as it will start and run for a short period of time as if there is fuel ahead of vp44 or something?
Also had to replace boost pressure sensor recently. The other day the truck had no power and check engine light came on. Scanned it and it said that it had boost pressure problems and scanner showed 15lbs of pressure with engine and key off. Thought that it must be bad sensor. Went and got new one(they gave me warranty on it), put it in and got truck started. Check engine light still on and code through dash is 433 - intake manifold pressure sensor circuit.
Any ideas would help alot

 

Did they replace your return line check valve on the VP44 when they replaced it? That is the next thing you should check if not. Clean it off and seal the small hole with your finger then try to blow through the end of it. If you can it is bad; if not then you have another leak somewhere. The injector tubes could be causing a return line leak. You could try to torque them to the correct setting or buy new o-rings, clean them, put Vaseline over the o-rings and reinstall.

 

could your fuel pump be taking a crap? what is the fuel PSI at idle vrs WOT? you may be intermitantly getting enough fuel to run right?