Are glow plug controllers open to the same huge variations in quality as glow plugs? I want a Beru Controller, not an Autolite.

I'm finding Echlin (Napa), Delphi, and some who do not list the mfr. They are all about $100.

I'm about to blow another wad on glow plugs - Motorcraft this time - and don't want to fool around with an old controller. I've been operating them manually, and am afraid I burned them out again (Delphi plugs)

 

If you are cycling them for 5 to 10 seconds at a time they should be fine.

 

I just cooked my third set of plugs. I'm getting Motorcraft/Bero plugs this time and I'm hoping they will be my last with this truck.

I was having a problem with the truck starting, then stalling immediately in cold weather. Unless air is being trapped in one specific area of the fuel system close to the injection pump - I don't think I have a fuel issue. I figure it was because there was no controller to cycle the plugs after startup. I tried "cycling" them manually, but am concerned that I could not mimic a properly functioning controller and burned plugs by giving them power while the engine was running.

I've spent $240 in glow plugs over the last few months, and am about to drop another $80 into the hole. I would just assume spend $100 on a brand-new controller and not risk burning up another set of plugs. The first set of plugs died from a controller that was bleeding power to the plugs constantly, the second got cooked by starting fluid while diagnosing an air-in-fuel issue, and I'm not entirely sure what killed the third set, but I've been closing the relay manually with a momentary switch which was working OK until the weather got really cold and I tried "cycling" them after startup.

I can buy a Delphi controller locally new for $107. I had bad luck with Delphi plugs and am thinking twice about the controller.

 

Are the glowplugs bad or are you just replacing them? I would check them first, but you are correct, the other brand glowplugs are a waste of money.

If the glowplugs were not working or a lot of them were bad, the engine would not start at all. I believe you do have a fuel system leak somewhere.

 

It was starting well while the plugs were working.
Starts fine when the block heater has the engine good and warm - I had fuel issues, but I think I've fixed them all.

I did a continuity test on the ones that were easy to get at - all open.

 

If you are down below 15, you may need afterglow, hit the switch for 5 seconds and the engine should smooth out.

When it goes below zero, you may have to repeat the after glow two or three times before it will stay running.

If your temps are at 30 or above, my guess is you still have an air issue.

 

Afterglow, Add to vocabulary. Sounds like something after a nuke went off. Our NEGITIVE degrees days are very limited but I have started it in a few. We hit almost 0* alot though. When mine starts, she don't exactly hit on all 8, cylinders (sounds like 2 with a broke rode) and chuggin like a baddly blowed headgasket. I have hit it with either that cold, it started it, it died very quick so had to do it again. Chug chug chug. Was like mom trying to wake my brother up for school. Now glowplugs should make this year easier.

 

That's the behavior I was getting with the manual switch arrangement. I'm just so tired of burning up plugs that I don't trust myself to handle the "afterglow" timing properly. I would trust a properly working controller better.

I never really did get my original question answered though - are there makes of controller to avoid? The easiest one for me to get locally is a Delphi. I'm just getting over the 3 sets of Delphi plugs - I want to make sure the controller is reliable.

Sorry to hear about your brother. Is your mom still having trouble getting him up?

 

Scout,
What year is your truck? The factory solid state controller for the 87-up 6.9/7.3's is pretty bulletproof. If you have an 86 or older, I'd suggest the factory controller for the 87 and up.

 

I have engines from and '87 '93 and '94. Right now I'm running the '94 engine and I think I have the '87 controller on it. I disconnected it and went manual after I found out all the glow plugs were dead, and there was 12V present at the plugs all the time. I don't know where it was coming from - it was still there when I unhooked the positive lead from the controller relay so I figure it was somehow being passed through the controller itself. The controller for the '94 has the underside sort-of melted, and I know the '93 controller is a dead-duck, so I figure I better get a new one before I invest another $80 in plugs. I can't be 100% sure what's killing plugs, so now I'm down to eliminating variables.

I assume an LED test-light should not "see" 12V at the plugs when the wait-to-start light is not on?

 

Are you sure it takes 12 volts to light the LED?

Most LED's will light with very little voltage.

I have 9 2.5" LED clearance lights on my flatbed plus 4 4" tail lights.
A 9 volt battery lights them all just fine.

The epoxy base on the 94 controller may just look melted.

I have a new stock controller/relay in my garage somewhere.
If it rains tomorrow I may be able to find it and see if it has a name on it.

 

Other than the afterglow, there should be no voltage going to the GP's when the WTS light isn't on. The underside of both my controllers looks "Melted" and I was told it was just the stuff they sealed the electronics with. With 3 controllers being questionable, I think you may need to check their wiring. Other than a bad relay, I've never had controller problems with either of my solid state systems. I wouldn't even consider bypassing either of them with a momentary switch. Not because I think it's a bad idea, but because I have that much faith in the factory system.

 

I would guess the LED will light on much less than 12V - but I'm concerned about any voltage passing to the plugs. My understanding is that the controller works on resistance perceived in the lead that feeds the plugs, and that's how the controller knows how long to cycle them. I can understand why there would be a very slight voltage present when the key is first switched on, but not constantly. Also, I would expect the voltage to be very little. Some electric trailer brake controllers (the ones that can tell if the trailer is connected) constantly pass voltage to the brake lead - this will light up my LED test light, but barely - like a tiny dot in the center of the diode instead of actual light.

My '94 controller may be good - I did replace the relay on it once. I took it off the motor because I thought it was not working - it turns out the plugs were all dead. Yes, I agree the melted portion is probably just the gook they seal it with - it's always been that way, even when it was working fine.

 

OK this is going to get a bit complicated so here is a picture to start.



Power goes in to the battery terminal at all times.
Power goes into the ignition terminal, but only when the key is on.

Glow plugs generate electricity when they are hot as in engine running hot.
A single glow plug will generate a current on the millivolt scale, never tried with all 8 tied together.

Next, the ignition terminal is powered by a wire running through the glow plug harness, so it could be leaking current into the glow plug circuit if the harness is damaged.

Also on the front of the engine, you have a fuel heater, timing advance solenoid, fast idle solenoid and fuel shut off solenoid that is powered from the ignition key.
This circuit also runs with the glow plug circuit in the engine harness, if it is damaged it could cross from one circuit to the other.

Ideal glow plug resistace shoud be between .5 and 1 ohm.
So each glow plug uses between 24 and 12 amps to heat.
8 Glow plugs at .5 ohms resistance would draw 192 amps to heat.

As the glow plugs heat, resistance increases.
The resistance of the glow plugs is what the controller senses to time the glow cycle.

So now what needs to be figured out is how much current is actually in the glow plug circuit.
The next step is to figure out where it is coming from.

Although anything is possible, the battery terminal should be the only terminal that power should go from to the glow plug circuit.

The ignition terminal and the white wire terminal are the two ends of the relay coil that triggers the relay.

There should be no way for the ignition terminal power to cross to the battery or glow plug terminals.

Likewise the ignition terminal power and the ignition power to the IP also should not be able to cross to the glow plug circuit unless the harness is damaged enough to have the insulation on both circuits damaged enough to short together.

The amount of electricity that will light an LED would not even make a glow plug melt frost off the tip.
With 8 glow plugs tied together, the glow plugs may be generating enough electricity to light your LED.

 

Thank you for the time and effort you put in to that response.

The glow plug system on this motor was very reliable on the last truck I had it in. I better check out the harness - I know the harness in the current truck has one section of harness chopped off where the AC compressor connected. I might just get the old harness from the last engine - it sounds like I need to check it over.