This is a friends truck, ‘85(?) I think, definitely a 6.9 but the truck has a 1992-1997 front clip. She sounds good when running but had some serious air leaks. My buddy didn’t have time to work on it, I was getting over a surgery so he got this “young guy” to work on it. He replaced the low pressure hoses, caps and I imagine the “o” rings, and the glow plugs.

If it sits very long, you have to bleed the air still, the young guy installed a check valve in both the fuel side and the return side but forgot to tighten one hose clamp and siphon she did. I could NOT get it to start, checked glow plug relay (GPR) and with test light it cycled on/off.

I checked glow plugs with test light, as I have always done so, and they didn’t light up. I removed one and read it with an DVM, no good and showed my carpenter buddy how to test the glow plug with a jumper cable. Would not get warm, all 8 bad.

He said the young guy changed them, he changed them himself once a while back. This truck has not driven over 20 miles, multiple start attempts but has fried the original set he purchased the truck with, the set he replaced,
​​​ the set the “young guy” replaced and now there are 8 that test bad.
Other than reading for even a trickle of battery voltage feeding through the GPR, what else is there to consider?

Thanks for looking, any thoughts greatly appreciated!

 

I will start by asking where he got the plugs. Motorcraft from a reputable source or you will have problems.
How are the batteries? What alternator is being used? Over voltage or charge voltage on the plugs can shorten the life of the plugs. Is the alternator staying off line when the plugs are lit?
I do not know much about that engine or setup but

Just a few thoughts....

 

I will have to check a little further, I helped him start it a bout a month ago, the batteries were new, alternator not good, so he replaced
it with one from Autoxxzx.

Since it wouldn’t start without ether I didn’t use that.

 

85 will use zd-1 glow plugs NOTHING ELSE.
you also need to check the controller to make sure it did not fail. The old style controller used before 87 failed in the on position and will burn out a new set of glow plugs in about 10 minutes

 

Glow plugs were Motorcraft, at least the current burned set are.
Checking this truck to check against another truck, this truck is an older (I think ‘85) with a newer front clip ‘92 or so.
Used my daughters 1994 Factory ATS turbo truck with 90+/- K on it.
This truck, the GPR control circuit has 11 volts on it the entire time the key is in the “on” position, the newer truck, after the GPR goes through it’s cycle, it no longer has voltage and ground on the control circuit.

I am starting to think I need to splice in a momentary contact switch to kill the GPR control circuit after preheating the cylinders.

Any thoughts?

 

agreed on the momentary contact glow plug switch. sound like the controller failed and is staying on.
once the controller is bypassed and switch installed, try 5 seconds switch on and see how it goes.
if it does not crack rite off, increase switch on time by 2 seconds each time to find the sweet spot.
with the ZD-1 plugs, it should be between 5 and 10 seconds

 

Installed a momentary contact push button and red light to show when control circuit was operating. Owner replaced glow plugs, I replaced the relay, it burned up another set.
I installed in line an electric fuel pump to bleed air out before cranking. Three attempts, maybe four and she started.
I let it run for a while, unhooked the electric fuel pump and had it run for a good while off mechanical lift pump.

He tried to start a couple days later, it started up, cut off and then no start.
Glow plugs are marked "BERU"

What is going on here? Between myself, my son and daughter we have 5 IDI trucks and have never replaced one (1) glow plug, let alone 3-5 complete sets.
Relays, yes. Glow plugs, no.

 

I wonder. Is it is getting 12 volts to glow plugs?
you need to check voltage of the plugs. if you have 6 volt glow plugs. I don't remember which plugs are 12 volt and which ones are 6 volt

 

Wow, something that simple would do it, will check.

 

Long time ago I did IH glowplug solid state controller conversion / retrofit on my 84 F250 6.9L and it's been trouble free ever since.

I'm not driving it much nowadays but it still works fine when needed.


Edit:
Looks like the IH kit 1809443 C96 (or C97) may still be available but price has gone up some.