So my '79 2wd Pickup just started having this issue, where once it's warmed up to operating temp, it just shuts off. NO sputtering, just cuts out. No spark whatsoever. I immediately thought it was the ignition module, but why would that be at all related to engine temp? It wouldn't. Not at all. Could it be the distributor? Do these trucks have a CPS? (Crankshaft Position Sensor) I've heard of those going bad and doing this sort of thing, but not on a 79 toyota. I am dumbfounded. I have to wait until it's cold again, and it will just start up again and run perfect like there was never a problem in the first place.

All my fuses are fine, coil/wires/plugs were replaced in the last month, and will be replacing the cap and rotor tonight, I'll post any updates.

Any thoughts would be appreciated.

 

Since you say it's not getting spark, how did you test it? You know it's not getting spark, or you're assuming it's not getting spark?

Just wondering, because if you have a way of knowing there's no spark, it's relatively simple to then narrow down which part is malfunctioning, unless you use the same method as me... I don't have the electronic testing equipment necessary to test the parts, but I know how to see if the plugs are sparking.

 

What I did was pulled all four of the wires off, and held each one close but not touching a steel bolt on the firewall, and normally i would see a spark between the gap, but there is no spark. My method is not professional, but it works. Hell, I used to even just hold on to the wire in my hand, if I felt a little shock, then it was firing, but no, it is not getting spark.

 

temp may not be the issue , age could be the problem .. parts wear out . might just be a coinsidance to the temp


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My '80 did the same thing a few years ago. There was a small (~12 gauge) wire that had a lot of corrosion on the end at the battery. I cut it back to good copper and soldered a new ring terminal on. No problems since then

 

I have had similar symptoms on other vehicles from bad connections that worked when cold but not when hot. I've also heard of coils working while cold and then being out of range when hot. If you have a multimeter you can check the resistance at both temps.

 

Ok, so I've got an update. But still not free and clear.

Earlier today I did the GM Coil/Module Conversion and the truck starts and idles pretty well. BUT, the moment I touch the gas, the truck dies immediately. But had no such problem before I replaced the plugs, wires, cap, rotor, coil, and ignition module.

I was thinking maybe something just broke. These things happen on trucks this old. Unfortunately I think it may be the carb. But I'd really like to hear a couple ideas.

I'm going to the parts store in the morning to get a voltage meter, will post an update of the reads I get.

 

I just had this on Tuesday. The GM module worked for me too... till I gave it throttle as well then dies. Get a volt meter, check voltages from coil positive, (should be right side terminal when looking at it from the front) and then ground to the screw covering the ignitor cover ontop of the coil. Should be 12 volts. If not try ground to battery. If that makes it say 12 then, then you lost your ignitor ground like I did. All I did was run a chassie ground to the metal cover of the ignitor, couldn't have worked any better. Hope this helps.

Or get you some aligator clips and get a GOOD chassis or batt ground and run it to the ignitor just for a quick test. But make SURE its a good ground. Like,sand a clean surface for the ignitor cap retaining screw.

 

see if this helps

http://www.pirate4x4.com/forum/toyot...il-30-a-5.html

 

That almost sounds like the fuel,cut off solenoid on the carb, after it warms up and cold idle is released there is no fuel available for slow idle, mine acted kind of like this and it was the ground wire for the fuel cut off, make sure your solenoid clicks when you turn on the key.

 

Ok, I'm going to do some work in the morning and let you know how it goes. thanks for your ideas!

 

My fuel cut solenoid went out, but warmth of the engine didn't really effect it. And actually, the only way it would keep running was to rev the gas. As soon as I let off the gas it would die. But I could drive it for hours as long as my foot was on the gas. It also only happened intermittently, but I know these things can manifest in different ways...

 

Well like I said earlier, the problem of losing spark is a thing of the past now. It sparks, and idles just fine now, but the moment i touch the gas pedal it dies now, SO, I'm going to the parts store right now to buy some wire to properly ground the GM Ignition module, and post the results afterward.

 

So I ran a ground to from the cover of the ignitor, to the battery, and there was no change.

This video shows what my truck does after about 5 minutes of idling. It NEVER did this before I replaced the coil and ignition module. I must have done something wrong.


Forgot to buy the damn voltage meter while I was in the parts store. COMPLETELY spaced it. But I'm leaving after I finish this post to go grab it. Will post an update after.

 

I tested my ground, and everything else, and I'm getting 12 volts like i should on the positive end of the coil, and grounding to the bolt on top of the ignition module. Im really at a loss now. I don't know what could be causing my idle to do this, and I can't give it any gas either.

 

Thats how mine sounded with the GM module. I'll look at my FSM tomorrow for more diagnosing info. Just curious, does your GM module, is it an AC Delco? Does it have the "GM" stamped on it?

 

No it was not GM, it's the Duralast version, http://www.autozone.com/autozone/par...er=115808_0_0_

 

ok just curious. My co worker who showed me how to do the GM setup tried it on his boat, and the boat had the same screwed up idle, but when he changed it to a AC Delco one with the GM stamped on it, it worked smooth. IDK if it was a coincidence or if there is some logic to the aftermarket durlast/echlin parts vs Declo, but i would hesitate spending $ on a Delco one just for a "test". Have you checked ohms between your wires on the distributor? But on the INSIDE of it. like under the rotor? If you notice where the cross to the inside they rub through a tiny grommet, and also get tugged on when the engine throttles up with the advance.

 

I'll run out to the garage and check, but this isn't the first duralast part that has given me trouble so I wouldn't be surprised. Also, I'm going to check the readings once the idle pulsating starts. Did your do the same thing? Bounce like that in the video?

 

I'm still getting all good reads. Going to return the module, and buy the delco one. Will update you when it gets here.