Glow plugs not lighting probably. Does the glow plug light come on? Does it have push button glow plugs?
1986 Chevy K20 6.2TD NV4500!! 4.10's (Name: POS Truck)
6.2 Turbo Diesel (HX40 CKO), 6.5 Serp, 6.5 Lift Pump, intercooler (to come), more broken or missing parts than you can shake a fist at, balls.