Looking for possible causes of a long crank situation I'm having with my 06 f350 6.0 diesel. The long crank situation seems to happen most often when cold. If I keep it plugged in over night it usually starts normal. After it is warmed up it seems to start normal but if it sets for several hours without being plugged in the long crank situation seems worse. Any suggestions?

 

I would start with the glow plug relay, make sure it’s working. If it is look at your glow plugs.
Do you get white smoke on start up after cranking for a while. Egunburnt diesel)

 

Haven't noticed White smoke when it happens but I will pay more attention to that next time.

 

Could be several things. Post this in the 6.0 forum to get more expert eyes on it. They will get you fixed up in no time

https://www.ford-trucks.com/forums/forum107/

 

I have the same symptoms. I went through the Glow Plug Relay (GPR) testing protocols with a digital multi meter and sometimes it seems to work fine, sometimes not. I also watched the dash voltmeter to see if/when the initial glow plug warming cycle started and how long it lasts. You can tell because the needle on the voltmeter will move up a bit once the glow plug warming cycle is complete ... about 90 seconds on my truck.

Apparently, the GPR problem can be erratic and not happen all of the time. Mine is worse when not plugged in and the ambient temps are 32*F or below. If the GPR does not kick in, mine cranks for a long time, it takes several attempts to start it and there is lots of white smoke (meaning unburnt fuel going out the exhaust).

You can search for my thread on this issue. I have purchased the heavy duty GPR from diessel-o-rings and when I have a chance, I will replace the existing one (which I think is the original) with the new, larger, HD one.

Hope this helps and good luck chasing it down..