Good morning guys and thanks for the feedback.
I left her unplugged last night; tried to start this morning and same od thing. She would only turn over and never start. I will answer the questions from everyone's feedback and see if anyone has any advice.
1- I am in Atlanta, GA. Last night it only got down to about 53 degrees and still wouldn't start this morning
2- The mechanical fuel pump was replaced less than 10,000 miles ago
3- Replaced glow plugs with Motorcraft ZD1A glow plugs within last two days
4- Replaced glow plug relay within last three days
5- The glow plug stays on for about 3 seconds, then shuts off and never comes on again.
6- It runs like a champ one it starts
7- checked batteries. Both were holding 13 volts and only sat on the charger for about 2 minutes before showing fully charged.
Some backstory that I may not have mentioned before: I replaced the fuel injection pump about a year ago with a cheap IP out of Florida. Replaced it again thre months ago with a mini-moose from Conestoga (recommendation from this forum and the truck runs like new once it starts.) Also changed the fuel lines. However, having changed the IP a couple times, there has been a significant amount of turning-over to get th fuel through the lines.
Starter turns over very quickly. Could the constant turning over from replacing the IP possibly fry the controller?
3 Seconds isn't long enough.
You normally see about 10 seconds on a cold start regardless of outside air temperature. 1987 and up IDIs use a better solid state controller that is smart enough to adjust the glow time based on feedback from the glow plugs, but 86 and down functions more like a timer.
So if you're running the OEM controller for that year, its basically a bimetal switch timer. Mine never really adapted cycle time based on temperature. It would either burn for 10 seconds (engine cold) or 1 second (engine hot). Didn't matter if it was in the middle of winter or summer - always 10 seconds for a cold engine. Its possible that yours is trying to cycle correctly based on resistance feedback, but is getting fooled into thinking the glow plugs are hotter than they really are (hotter glow plugs have more resistance).
Ok, how have a look at this photo of the wiring on the passenger side inner fender (an old post from my FTE days):
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See that grey connector to the upper left of the black plastic sphere? That's the main engine harness connector. Not many wires since its an IDI
The bad news is, its not weather sealed with anything but some grease from the factory, so its prone to corrosion. Now see those two, heavy orange wires right next to it? Those carry the current for the glow plugs. In this photo, I've cut the orange wires and bypassed the connector after finding it melted. I my case, I was still getting the normal 10 second glow time, but much of the power was being lost at that connection due to higher resistance.
Something else you can do is manually bypass that relay to the lower, right hand side of the black sphere. If you can hold this on for 10 seconds, and it fires off normally, you found your problem.
In the end, I fitted a switch for OFF/AUTO/ON to control the glow plugs. Sometimes Auto works, sometimes it doesn't. At least this way I can still take over control.
Oh, and as for a drainback problem, that doesn't seem likely since it fires off fine with the block heater. If the engine was starving for fuel, it would sputter either way after sitting over night.
