Starting problem
 

When my truck sits over night only when real cold out, and I can go out and try to start it sometimes it will crank and crank, puffing white smoke out. I can turn the key off and try again, and sometimes again, then finally I shut the key off and try again and it fires right off. Kind of sounds like my glow plug controller is not letting the glow plugs come on. Would the controller be going bad? I have brand new Motorcraft plugs. It just seems like there not coming on then ill reset it by turning the key off then back on then it works.

can you watch the voltage drop and then return to normal while they are cycling?how long are they cycling?you can always put a push button in.how do the return lines look?

The light stays on for about 15 seconds. Id like to keep it where it comes on with the key. I do have another controller. I just want opinions on if thats the problem. I think its a glow plug issue because if I turn the key off and back on it fires right up making me think the GP's are not working all the time. Never payed attention to the voltage, Do I want it to drop?

Well I went out and turned on the key and the voltage went up just a little, not even to the N in normal. When the WTS went off and clicked once or twice the voltage moved around a tad bit but didnt go all the way up.
I may just hook up a switch to see if it works.

The cold weather taxes everything, but batteries the worse. And themetal block is colder making it harder for it to reach hot enough temps to fire, it is possible that the starter is not spinning it fast enough too.

Dab some dielectric grease on all the controller connections. Mine was loose the other day and it failed to start. When i tightened them up, it fired instantly. Just a thought. When you turn the key to on to get the wts light to come on, there should be a drop in voltage, a load is being applied and a large one at that. When it releases or the light goes out, the voltage should rise. If you are still having issues after all that, check the GP's then load test batts and a final question, how old is the starter?

Relay contacts do were out.

It is possible the glow plug relay contacts are pitted and not carrying full current to the glow plugs.

When everything is working right, about a 2 volt drop of the volt meter while the plugs are heating is what I usually see.
When the glow plugs turn off, voltage increases about 1 volt.

From your glow times, they sound about right, so the controller sounds like it is working.

On the new style systems, you can replace the relay with a glow plug relay for an 86 old style system at a cost of 30 dollars versus 150 for the new style controller/relay replacement cost.

If you turn the key on and off several times

Also the chassis to engine harness connector near the dip stick should be checked for corrosion or signs of overheating.
Any corrosion in that connector limits how much electricity is making it to the glow plugs, which will affect how well they heat and how well the engine starts.