Fairly new to both the diesel world, as well as the truck owning world. Currently I am working through a starting problem on my 1991 F350 supercab. Just replaced the relay and controler. Still no start. I plan on replacing all glow plugs this weekend, in the hopes of solving my problem. The WTS light stays on for three seconds and then turns off. I tested all of the glow plugs before and the resistance showed either 0.5 or 0.5 ohms each. Even though they should all work, I am going to replace them all so I know what is in the engine (motorcraft ZD9's) (I just bought the truck two weeks ago and now I can't get it out of my driveway). If the glow plug replacement doesn't work, I need to get my truck towed to a shop to get it running again. I live in University Place, Washington, just outside of Tacoma. Any suggestions on a shop would be greatly appreciated. And even better would be if any of you all out there live near by and could help teach me about my new truck. I am all about learning to work on my new truck. Thanks in advance if any of you have some suggestions.

 

3 second WTS sounds like glow plugs, sounds like youre on the right track.

 

Just out of curiosity, is it common to replace the glow plug wiring? Most of rubber boots on the connectors that slide over the glow plugs (the newer round plug style) are long gone. I can see the metal connector only.

 

The boots are known to fail, no big deal. The connector can be replaced if its in bad shape, or just put some heat shrink tubing on to insulate it.

 

You could try plugging the block heater in for a few hours. If it starts then, that would also indicate glow plugs...

 

Welcome to the IDI world, your in luck western Washington is kinda IDI central so it seems, probably Justin's fault, lol. I'm localish, Kent.


Sounds like your on the right track working it out, a couple suggestions. I found mine to be rather throttle position sensitive at times. The visor says something like half to full throttle for starting, mine starts much better with no throttle, just a little tap to make sure the cold start fast idle is set, experiment with yours. It might also be worth while to set up a manual glow button. A push button connected to ground connected at the white wire on the GP solenoid. This button will override the controller and power the GPs manually. This can get you started in a pinch but needs to be used very carefully, it's easy to burn up your glow plugs.


As for shops, I can't think of a single shop I'd trust an IDI to and would be willing to pay for. In todays world the IDIs simplicity is too unique for the modern computer reliant parts changer. Nor is anything about them really that hard to do yourself, and really that's half the point isn't it.

 

If you really can't get the thing running, disconnect the glow plugs and use a bit of ether(doesn't take much, but can be a lifesaver when things aren't right).
Make sure you are getting fuel first(see this video):


This is true.
Hm... I'm thinking Justin needs to start a side business here. I'd trust him to work on /my/ IDI.

 

Thanks for all of the replies so far. So here is an update...I had a mechanic friend come by yesterday to help troubleshoot. Mind you I just replaced the controller/ relay last weekend (no glow plugs yet, even though I do have a replacement set). When testing the system, my initial symptoms remain the same:
WTS light on for 2-3 seconds, turns off, and clicking under the hood

Whats interesting is that there is no voltage going to the glow plugs. We were able to bypass the controller with a 12volt bypass using a jumper cable and the truck fired right up. My friend suggested returning the controller, and replacing with another. Any other thoughts? Mind you these were the same exact symptoms I was having a week ago before replacing the controller. Is there a fuse in the WTS relay that connects to the controller that may be stoping voltage from getting to the glow plugs? It seems like there is something fishy going on.

 

Oh and one other update. I learned I do have a block heater on the truck and have had it plugged in all night (40 degrees). Unfortunately, it still won't turn over however. Is there any way to test if the block heater still works? Thoughts there too would be appreciated.

 

The glowplug controller uses resistance from the plugs to determine glow time. If one or more plugs are out it will see something is wrong and not glow. Replace all plugs with motorcrafts if the issue persists replace the controller.

To test the block heater you can slowly plug it in and listen for an arc. Or plug it in and put your ear next to the passenger front tire, you should hear gurgling/etc.

 

If you jumped the glow plug relay and she fires right up, then the PLUGS work fine!

Sounds like the classic "positive wires melted into the harness" issue.
If you grab the wire loom on the passenger side off the glow plugs and follow it back towards the blower motor you'll find a grey connector with about 10 wires on both sides. The two thicker yellow wires are the positive leads to the GP harness, check that connector for melting and corrosion, it's classic.

Quick terminology review:
Engine turning over=batteries power a starter motor that spins the engine at low speed.
Engine firing/catching=combustion takes place and then the engine runs.

So after you plugged in the heater does it not turn over? Or will it not catch/run?

If you have good battery power to the starter and it turns over quickly, the engine should fire if the block heater was working. So I'd say you've already tested it, lol.

 

I'm not sure how the GP controller would react to not having enough power but this is something worth checking out. There is a plug in the power supply to the GP controller. This plug is known to go bad, circled in red in this picture.



The above picture is an older truck and I think wire colors are different. But you'll have that same plug in the same location. The plug will have two large wires that are the same color on each side but different on opposite sides. IIRC for your year black with a yellow or orange stripe on the fender(supply) side, yellow on the engine side. These wires supply the power to the GP controller. The supply side connects to the large upper post on the starter solenoid.


Worth while to check that plug, the wires, and the connection at the solenoid. Not only that the connection is good but that they aren't getting too hot during glow.


Edit, Josh beat me to it, lol.

 

As far as the block heater. Make sure the cord is plugged in to the heater. It is located above the starter on the passenger side of the block. If it is plugged in, then use a meter to check continuity across the end of the plug. If there is no continuity, then pull the cord going to the block heater and check it for damage. You can either repair it or purchase a new cord. I had to repair mine in a couple of places.

Also, how quickly does the engine turn over when cranking it. Turning over too slow can make it difficult to start as well.

 

So here are the pictures of my controller and some of the wiring going to it. This is actually a photo of the original controller I replaced last weekend. However, the photo with the arrow shows the terminal I used to jump the truck yesterday. + on the battery to that terminal for 10 seconds and the truck fired right up as usual. Here are the links to the photos:


http://1drv.ms/1USN2iH

http://1drv.ms/1USNc9S

P.S. This is my first time trying to use Microsoft OneDrive so please bear with me if the links don't work

 

I stand corrected on my terminology. The engine has been turning over this whole time. It is not firing or catching. Thank you for clarifying my words Josh. It helps if I speak the right language