Went thru a lot to find this.
Replaced fuel & air filters. Fuel bowl clean, green diesel out the water separator.
Noticed slight fuel leak on return fuel line F7UZ9S274BB replaced.
Still no cold start! Aaarrrggh!!
Good fuel pressure from fuel pump.
Let sit for 2 days & HPOP reservoir still nearly full.
Checked power output on glow plug relay - good
Checked power output on fuel heater relay - nothing Alright now were onto something!
Removed relay, tested relay on battery & it works. Back to its connections, live battery power good, key on positive good, no timed ground from PCM. Found the relay controlling the solenoid / relay & changed it to no avail. Ran the jumper wire then she fires right up after sitting for 2 days. THANK GOD!!!!!