A little while ago my truck started act funny. You would get on it and then when you would let of it would "fast lope" idle real rough and eventually clear up. Well yesterday I got on it, it started running rough then died and wouldn't start back. I sat in the middle of the road for about 10min trying to start it before I got mad and used the starter with the truck in gear to pull it out of the way. About 20' of that and it fired right up. Any suggestions on what it might be? Only happens after getting on it.

Use a scanner and check for any trouble codes being set first.

3 minutes ago, 01_Cummins_4x4 said:

Use a scanner and check for any trouble codes being set first.

No check engine light

Certain codes can be set without a CEL being on.

 

Do you have gauges for fuel pressure, boost, and EGT? 

Edited March 18, 20223 yr by 01_Cummins_4x4

Yeah it would be a fuel pressure gauge reading. It sounds like the lift pump could be getting weak, suction air leak, air drawn in could cause VP44 air locked. By the time you did the long crank it was enough to purge the air out.