Does anyone know what the OEM part number is on the glow plug controller for a 1991 7.3? Also, what is a good brand of aftermarket GP controller? I know the Autolite gps are worthless. Is there an aftermarket GP controller that is as good or worse than the original Motorcraft part? Thanks.

 

What is wrong with your present controller ........

 

Shorted out I was having starting problems and was going through the motions and testing it and it was shorted out. I am going to replace it but I want some advice.

 

Cheapest place I know....... http://www.mwfi.com/dieselPage/ford_73.htm

Make sure the wires are connected correctly search FTE for controller pics there were some recently.

 

 

I just bought a 89 diesel used and my glow plug controller has the remainder of a red fusible link on the battery+ side of the controller. The controller will work sometimes and the rest of the time will be very erratic and not send voltage to the plugs. I just checked my plugs tonight and had 1 bad one. I change it out and check my voltage, and I get about 8.5 volts to the plug. Is this good ? Do controllers "wig out" when they are going bad ? Thanks for any help. I absolutly love the rattle and smell of my great new (well used) rattler.

 

No wigging out that I know of, but 1-2 GPs out will change the GP controllers operation drastically.............

If you have 2 or more bad GPs, the controller may not cycle at all.

Two problems that occur with the solid state ( 1987 to 1994 IDI engines ) GP systems. If a GP burns out ( circuit resistance goes up ), the controller cycles the GPs at a faster rate which doesn't let them get to max operating temp. If 2 or more GPs fail, the controller may not cycle the GPs at all ( very rapid or no clicking heard ). When you check the GPs, use an ohmmeter. A high resistance ( not necessarily burned out ) GP can cause circuit resistance to go up and the controller will then cycle the GPs too fast. You probably will not find this problem with a test light. Resistance spec for GPs = .5 to 1 ohm cold. Second problem. A poor controller ground ( black wire attached to valve cover stud ) will cause the controller to leave the GPs on longer, often damaging or failing them. If you are having mulitple GP failures, I would check closely the controller ground. Now the confusing part. Bad ground --> longer GP on time ( slower cycling ). Burned out GPs --> faster cycling If you have both situations, it may appear that the controller is cycling the GPs at the proper rate. Bad ground slows it up while the burned GPs speed it up ---> normal cycling. The system acts/sounds like it's working normally, but you have a hard starting concern.
DieselDon

Glow plug torque is 12 ft lbs, I always use antisieze on the threads.

 

I had 1 bad glowplug and now it at least trys to cycle the plugs. The light stays on longer, at least 10 seconds, vs the 2 or 3 before. But the truck still starts very hard, taking me 2 or 3 tries of rolling for 10 seconds or so. I checked each plug with my fluke and the resistance is from 2 to 5 (.2 to .5) on my meter, while the bad plug was just plain open. (the new gp was .2, the older units in the truck were .5) I also checke the voltage and it only goes to about 8 or 8.5 volts at the plug for the gp. If this all looks correct to you, i will check my ground and hot lead for connections.

this was a farm truck and was not maintained as well as it could have been. I bought this very cheap. Its seems to run great and drives great, but needs maintenance.

 

I think the fuseable link needs to go away.
Never saw one in that location.
With the voltage drop when the glow plugs are heating, 8.5 volts is about right.
They draw a lot of amps when heating.

 

You might also check and see if you have a problem with your return line in this warmer weather you should not have that hard of a time starting your truck even if you your plugs are not cycling right sound like it could be a fuel problem.

 

its been staying in the mid 90's here for the last month or so. when I got home yesterday, it was still 92 out and I had to cycle twice before it would start. It seems to me that the WTS light is only on for abour 4 or 5 seconds, instead of the 10-12 seconds I thought it was. Before, I had to plug it it, hit it with ether and crank to get it running, now it will at least start on its own. Do you think I may have more bad glow plugs ?

 

you might have another bad glow plug but your truck should start right up in this warm weather. regardless.

 

would a bad fuel pump cause starting problems ? I had a friend hit the bleeder as I was rolling it over and foam rolled out, just full of air. I am just grasping at straws here. Once running, it has plenty of power and will roast the tires. I am planning on changing all the glow plugs this coming week just to be safe. They are fairly inexpensive and easy to do.

Now, If I cycle the glow plugs 3 times (at 4 to 5 seconds per cycle) it will start after maybe 10 seconds of rolling over.

Another thing, could the fuel system be just dirty ? This sat for almost 2 years of minimal use and just plain sat in the weeds for 7 or 8 months.

 

It sounds like air is get into the system check all your return lines for leakage if they are old and and dried out you could be getting air in from there. it is probley a good time to change your filter get a good one (not a fram)and just plug off the return line where it feeds back to the filter make sure you plug the line and where it hooks back to the filter. also make sure the lines coming off the injector pump are snuged up on both ends. I dont think its your fuel pump.

 

I checked the truck over today and did not see any signs of weeping. But, the return lines do look original. I will try replacing them next and see what happens. Thanks for the help.