Glow plug wiring.

[offroadohio]

Ok, as some of you know ive been having alot of issues with my 87.

I am down to my final issue. I repalced the starter and soliniod with all new today, I also replaced the alt, and the voltage regulator.

the truck cranks right over and fires up now, but I'm still only getting 10amps from the alt. If I turn the headlights on the lights get bright and then dime, birght, then dime. When I first turn the key on the WAIT TO START light comes on but doesnt go out. I sat for 2 minutes today and it remained on.

I started the truck, and with the door open I watched the dome light go bright/dime. I popped the hood and the gp relay was clicking on and off, each time, about every 2 seconds, Its obviously drawing a TON of amperage as when it clicks on the is when the lights go dime. I let it idle for 30 minutes doing this and it never stopped. The last time I drove it, I ran it for over an hour on the freeway doin this same thing.

I didnt have this problem until I repalced the glowplugs and the gp relay. Is it possible I have a wire in the wrong spot on the relay?

Could it also be possible the cold start sensor on the IP is triggering it becuase the pump is shot?

Here are some photos of my relay, does everything appear to be hooked up correctly?

Should both of my small yellow wires be hooked to the same post on the relay?

 

[offroadohio]

If I unplug the cold start thing on the ip once its started will it run?

If so, which of the two wires is it?

Or, am I tlaking out of my butt, completely not undewrstanding how this thing works?

 

[TLBREWER]

Could it also be possible that you got a defective relay?

Tom

 

[offroadohio]

Already replaced it again it had no effect.

But, now I'm really confused.

My truck is an 87. The engine I put in it is from an 87.

both engines were identical to each other.

But, when searching glow plug controller, I find this listed for 83-87, which is listed as fitting the 6.9

You must be registered for see images attach

And this listed from 88-94 which is listed as fitting the 7.3

You must be registered for see images

Its obvious that the two parts are totaly differant, and i cant find anything listed as fitting the 6.9 that looks like the second photo.

If I buy the 88-94 style new will it work on mine?

 

[offroadohio]

What wires do I need to unhook to kill power to the controller, while still letting it run? Its warm enough I should be able to fire without the GP's until I can install a new controller to see if that fixes it.

 

[TLBREWER]

1987 was a transition year. The trucks got the new body style, but kept the 6.9. Here's a good read about the changes thru the generations if you haven't read it already. http://www.oilburners.net/forums/showthread.php?t=14615

I don't have any 6.9's so I don't know which way to point you. I do know the 6.9 and 7.3 have different glowplug systems, but I don't know the specifics enough to give you an intelligent answer.

Tom

 

[SKimballC]

Your GP relay is not stopping its cycle. Maybe something is hooked up wrong to the relay. You are going to wear your new glow plugs out with them cycling the whole time your truck is running. Anybody around here have a schematic for offroadohio to compare his wiring to?

 

[The Warden]

Anybody around here have a schematic for offroadohio to compare his wiring to?

I have these two...the first one's straight from a Ford manual, and I found it quite confusing. The second one, I'm not certain where it came from, but it makes a bit more sense.

I tried to wire a 7.3l controller onto my 6.9l, but I never got it to work properly...the plug only cycle once, and only for about 1.5 seconds. I used custom wires, and I think I have an issue with my wires giving too LITTLE resistance to the plugs, so the controller thinks the plugs are already hot. I have a 7.3l wiring harness; just, haven't had any time to play with it. I used those two diagrams and a tester to figure out what wire went where...it's actually easier than it looks And, yes, the 7.3l controller is what you need for the '87 6.9l.

 

[offroadohio]

My wires are correct according to the schematics. When I swapped relaysI unbolted the bad one, and bolted the new on and then unhooked each wire, one at a time and hooked them to the new.

The glow plugs havent worked correctly since I swaped this engine in. I thnk the control module almost has to be bad, the old stuff worked perfectly.

 

[offroadohio]

hmm. I unhooked all wires, then hooked them all back up in the same location. Everything worked fine for the 4 times I've started it since.

Tommorrow I'm going for a 1.5hr one way drive. I'll see if the GP system works correctly tommorrow. If it does the next task is to change the IP.

 

[Wanderer-rrorc]

the manual for my 85 (yes it still had the factory manual!!) said if it keeps cycling..to shut it down and restart...sometimes they hang up...

I dont know what the one on the van looks like...I'll check it tommorow and let ya know...(if I can find it!!)

 

[offroadohio]

Mine was doing it everytime it started, not just on occasion.

I'm getting ready to roll out to ride stoenquarry. I'll see how it does.

 

[Mr_Roboto]

There are two different glow plug systems, the 7.3 system was used on the last year of the 6.9.

The 6.9 system uses the controller that screws into the drivers' side ehad (first pic) the 7.3 system uses a controller mounted on the rear of the intake manifold (second picture).

The pictures you posted of your truck show the "solid state" 7.3 system.

For a quick fix, you can wire a manual control for the GP solenoid. REMOVE the white wire (that's the wire that the controller switches and the controller is likely the problem) then run a wire from that terminal, through a pushbutton switch and to any good ground. When you push the button, the solenoid will close, when you release it it will open.

I would not be surprised if your glow plugs are burnt out if they have been on as much as you say. Use extreme caution in removal as the tips may be swollen from overheating. A tip breaking off can destroy a motor if run.

 

[offroadohio]

Have taken the truck on two 3+ hour trips since I replaced the GP control. I must say thats the best $100 I've spent on this thing. I havent had a single cranking issues since I replaced it, no more hot wires, and no more dead batteries. Starts everytime, and the relay immediately clicks off, and away I go

 

[Agnem]

The 87' 6.9's were the best ones. The snuck some 7.3 features like the glow plug controller onto them. They may also have the 7.3 rocker arms but I'm not sure. Don't let those non-Ford parts manuals confuse you. When shopping for glow plug stuff, just tell the parts folks you have a 7.3. Does your glow plug harness go off to the drivers side of the engine, or the passenger side? If the passenger side, then you would have a very unique one year only wire harness, so don't burn it up.