I have an f 350 , 05 with 6.0L deisel. It has an 120k, I'm having trouble with hard starting after its been running or is warmed up already.any answers to why this may be happening.
ThanksHVAC guy

On diesel engines that will not restart, after they are warmed up, it's often a sign of a tired fuel pump. As they heat soak, inside pump head clearances increase and it will no longer develop sufficient fuel pressure at cranking speed. While it's running, fuel helps cool the pump by carrying the heat away. Try installing a new Motorcraft fuel pump. I would also replace both the under frame and under hood fuel filters, if they have not been changed recently.