Okay, so I'm still driving the old 1988 diesel Ford. When it runs it's awesome, its getting it started that's the problem. . . . . again. Having read through all the glow plug related threads I could find I can't seem to find anything similar so I'll start a new thread.
Truck doesn't want to start or is hard starting when cold. Starts when on the block heater for at least 2 or 3 hours are fine. The Wait to start light comes on, I hear the relay click on, but I do not hear the on/off cycling after 10 or so seconds. I do hear the relay click off after about 20 to 30 seconds. I'm wondering if there is a problem with the glow plug wiring, which I have replaced a few years ago when the original harness deteriorated. Or do I need to replace the glow plugs. I have tested them with a circuit tester and they seem fine. I also replaced the controller and relay about 2 years ago, alternator and voltage regulator 1 year ago, and batteries 1 month ago.
I must admit that in a pinch I will disconnect the glow plugs and use a starting fluid to get things going when I need to get to work and haven't plugged in the block heater.
Thinking about ditching this beast and buying a gasser. There is a nice '96 F150 with the 4.9 straight 6 and a 5 speed for sale in my town. Would like to keep the beast though, hard to argue against 19 MPG in a full size truck.

 

How do you disconnect the glows? Mine are too hard to get to to do each one at the plugs itself.

About 1/2 sec shot of ether and she starts immediately.

Sounds to me your electrics are working normally. Have to checked the level of fuel in the fuel filter? If its not FULL when cold perhaps air os getting in there or the fuel pickup on the tank is shot.

Just my 02.

I would start it with just the tinnest shot of ether until it blew up (or not) Then get a new one.

 

first off, what brand glow plugs are in it?
secondly, did you test to see if voltage is going to the glow plugs?
how fast is it turning over?
if the starter is tired, it will not turn over fast enough to start when cold.

 

how long does the WTS light come on for?

 

I'm using Beru Plugs.
I think it's turning over fast enough.
The WTS light comes on for around 10 seconds.

 

i am having the same problem as you are right now. my wts light stays on for 15 sec, then goes out but the plugs stay on for another 10 sec. i get no clicking from the relay now.

your issue sounds like something other than plugs though. my truck will start just fine with my plugs doing what they are doing.

 

My 1988 F250 starts just fine. Te WTS light doesn't come on

 

to the OP= sounds almost like there is a malfunction in the controller or solenoid, like it thinks its working but not. On my truck i had the controller hooked up but the solenoid disconnected and the WTS worked as it should, 8-10 when cold and 1-3 when warm. But obviously the plugs werent getting any juice. So as mentioned above, i would verify that the plugs are getting juice when they are supposed to, and if not i would start at the solenoid.

 

I installed a push button system to run the plugs manually. I've already replaced the controller about 2 years ago and don't need to do it again. This is a lot easier even though I have to sit there with my thumb on the button for 20 seconds before I turn the engine over. Just wired it straight in to the relay, and unhooked all the wired from the controller. It's still a bit tricky to start when cold, but it's better than it was.
What about using a starting fluid in the 7.3 IDI without glow plugs? Would that really screw up the engine? I know the glow plugs can ignite the fluid before the cylinder gets to the top so it can damage the engine that way, but if the glow plugs are unhooked is it still that bad?

 

The only wire you need to unhook from the controler is the White wire, tape it off at the end. the Blue wire goes to the WTS light. the Black wire goes to ground, you need that. make sure it's clean and making good contact. the Red wire needs to be hooked up to make the realy work when you turn the key on the Red wire with the Green stripe goes on the same post as the plain Red wire. how did you hook up the by pass wiring?

 

I use just the littlest squirt of ether into the air cleaner. Then I turn on the ignition, wait for the red light to go out, wait for the clicking to stop, then start it. It starts pronto. Mine also runs OK and starts instantly once warm. About 1/2 second squirt will do the job. I would bet the problems happen when people get enthusiastic with the ether.

I could be wrong.

If the white wire is all you need to disconnect then maybe you could put a toggle switch on it. On for plugs without ether, off for ether starts.

 

Just curious, does it sound like its catching every once in a while. And then finally fires within a few starting cycles?

One thing I found by accident is just how bad my air intrusion on my truck was, allowing fuel to drainback after being shut off.

I was putting in an injector pump/injectors as a tuneup and clear lines in the engine bay so I don't have to touch the truck for a while and decided to go with a carrier electric pump.

Now I have to get in and let it run for 10 seconds before starting it BUT the truck is a totally different vehicle now. Before I was scared of running the batteries down low.

I put my glowplugs on a push button and go out there for the first start of the day and hit the glowplugs for 10 seconds then let off and turn the truck over and it starts within a few seconds.

Once the truck runs it is smooth. We never had such bad air intrusion that bubbles were constant to make it shake and puff white, but definately enough to drain and take fuel out of the filter overnight.

 

that's the ticket!

never again will you ever guess about your engine getting fuel.you just always know it is.
your starter knows it too.