Might be a fuel problem-- the glow plugs on my LLY cycle fast. Also the LLY does not have as much problem with glow plugs as the LBZ. If you don't have any glow plug codes, I doubt that is your problem.
Try pumping the primer on the filter housing, see if that helps it start.
Chevy 04.5 LLY, 2X, shell, XDR, MikeL Heavy duty up-grade, 6spd, TransGo, deep pan, de-badged, 65 Gallon replacement Aero tank, LBZ-mp, Kennedy pump, shimmed, Pre-fuel filter, tow mirrors, BU cam, gauges, GPS, Sirius, bags, custom grille, fender vents, HD trans cooler- Curt front hitch, footwell lights, load lights, Studs, head gaskets.--- Jerry