Hi guys,
Got a little problem that's really boggling my mind and I wanted to see what you all thought. I searched through the forum and I had no luck finding a related post. If someone has posted about this, I would love the link to the article. I have an 82 4x4, 22R with 208k on the odometer. Here's what's going on:
1. Some times when the truck is cold it won't start at all. Feels like it's just turning with no spark.
2. When warm, I get on the freeway and after about 5 minutes (60-70MPH), truck just stalls and dies. I pull over, crank it and it starts up. As I approach highway speeds, it dies again. This problem also happens when I'm going up a steep hill and the engine is under load. It rarely does it when driving on the street. Seems like highway speeds and higher engine temperatures play a key role. After I've turned the truck off and let it cool, it'll some times not want to start up again. It'll turn over but it doesn't seem like it's trying to start (seems like there's no spark).
3. With ignition in the on position (engine off), there's no power at the plug that comes from ICM (ignition control module) and connects to the distributor. Should I have power there with the engine off and key in the on position? Or only when engine is turning/ running since that's when it's sending a signal to the distributor to spark?

So far I've rebuilt the carb, replaced ICM and coil and the problem still exists. I've replaced the ICM 4 times. FOUR! Could it be that I keep getting a defective ICM from O'Reilly? After that many times? Taken it to 2 mechanics (Great mechanics at that. These guys are no grease monkeys.) and they too are baffled. Also, I'm wondering if something is heating the ICM up to a temp that's causing it to stop functioning. Is that possible? If so, what could do that?

Thanks in advance!

-Manuk

 

...or is this a fuel delivery issue...hmm.

l’d say get “something” to test your thought about not getting spark when trying to restart it & you think it’s not getting any spark. Maybe it NOT an electrical issue?

 

Appreciate the suggestion. I have tested it and indeed there is no spark. I'm more confused as to why there is no spark.

 

To diagnose no spqrk, work back from spark plugs. Take a plug out, ground it on engine block and test for spark, move back to wires, then distributor then ignition coil. All you need is google and a multimeter

 

My hunch is youve got an overheated wire or contact somewhere thats been burned at some point. So at normal temp its normal resistance but when hot it separates and cant conduct to spec.
To diagnose, maybe run your engine in the driveway or arnd the block til engine bay is really warmed up.

Icm should be 12v hot with key on. Key start position fires your starter. Fuel pump, ignition, etc is always live except accesory position.

 

a word abt mechanics: they dont like troubleshooting electrical problems, time consuming and expensive for them and you. Most mechanics have the skills to do the job but couldnt make it worth their time.

Ivan could also be right abt fuel. But no power to icm sounds like somewhere to start.

Have you searched the forum? I feel like someone has this problem every week. There is a wealth of threads abt tracking down no start/no start hot conditions.

 

Might be worth a look?
https://www.yotatech.com/forums/f116...-cause-105475/

 

Sounds good. There are 5 plugs coming off the ICM.1. Coil. 2. Distributor. 3 and 4 I'm not sure what they power but one of them has 2 contact points and the other has one. And the 5th plug that's just empty. Not sure why this 5th plug is there but it doesn't connect to anything. Which one of those plugs should be at 12v with the key on?

 

5th could be your tachometer signal wire. Not sure though. Search for an electrical diqgram, it will tell you wire colors so you can track what goes where.

 

https://motogurumag.com/i/1983-toyot...am-GIGwpYv.gif

Thats an 83. Dont see an icm on it unless Im missing it somewhere.

 

Thanks

 

Im trying to track down which your 12v power to igniter should be. Possibly Black with r3d stripe?

locate your ignition fuse and see what color wire is coming off the back of that. this wire should go direct to ignitor.
also check your fuse and the contacts in fuse box. They can get corroded.

Does your fuse box have a 15a engine fuse?

I have a 20r so im not too familiar with 22r wiring. Sorry

 

Ok black and red wire Br should be from ignition switch.
Your open wire at ignitor should be blue, for a tach which you dont have?

Im trying to figure out where white/black wire goes.

Haynes manual.

 

Wb should be a ground on left front fender. Idk why bc the ignitor grounds to the fender by its mounting bolts...

So Br should have 12v with key in ON position. One test lead on Br, one on a good ground.

 

Also, the Br wire might be coming off the ignition switch, not the fuse.

 

Swampedout,
Thanks for the response and the help. I'll number my answers so it's easier to keep track:

1. Mine is an SR5 so yes. I do have a tach.
2. Yes I have a 15a engine fuse and it looks good. Double checked it.
3. Located the Br wire on the ignition switch. In the on position, with a good ground there's 12v power to it.
4. Found the Wb wire on the ignition but I can't find where it's grounded in the fender.

 

Hmm. So what color wire dead ends at the igniter?

Have you tested your ignition coils resistance?

 

And have you tested resistance on spark wires? Old or cheqp wires could have thin metal or cheqp insulation that fail when hot.

Hopefully 13swords will chime in. Hes the pro on ignition issues.

 

Swampedout,
There are two plugs coming into the igniter. One of them has a brown wire the other one has a black wire.

I haven't tested the ignition coil because it's brand new. I haven't tested the spark plug wires resistance either.

How old is too old for spark plug wires?

 

Had the same problem with my '81. Took it to three shops before it was resolved. Failing coil ignitor. When the weather or truck was cool/cold everything was Ok, when warm or hot the ignitor would stop working randomly resulting in no spark and stalling. Your options are a good used ignitor or a new GM ignitor from the early 1980s. The Toyota ignitor is no longer available new and was priced at over $500! My mechanic used the GM ignitor and has it been working fine for the last 5 years. Hope this helps!