[diehard150]

Its a bit frustrating with the older 7.3 Idi's and I had the same problem with mine! As mentioned the fuel return lines are a huge part of hard starting with those, Then came the wiring to the glow plugs(check connections and overall condition of harness). You want a snug connection to glow plug tip. I've also noticed that where the harness that connects to a main wiring harness wires had melted from over cranking the motor(check for that). Once I had that all figured out then came the cold weather, I plugged mine in at 45 degree's everyday for an easy start. Most of all that motor is picky about oil changes, every 5000 miles I did mine. I relied on that truck daily for my Business and took good care of it and it took care of me. Good luck