my SC starts fine, but I can't keep it running, doesn't seem like the usual problem

[jtfreels]

My car, an 82SC has not been running for a couple of months, I've had some previous posts, but I'm starting a new one to sum things up and hopefully get to the end of this.

It all started when.... I was driving down the street and the car just died, like I had turned off the key. It would not start up and I had it towed home. The next day the car started, I drove off for a bit and it stopped again.

In short the car will start up fine, run for about 5 minutes or so and then just quit. Once it stops it appears that I have no spark. After this the car would not start at all.

The first thing I did was to replace the "green wire" this was very stiff and appeared burned. I had to splice in a connector as the original was one wire.
After doing this the car started easier, but still the same symptoms, cold start fine the quits suddenly.

Thinking this was my CDI box, I have replaced it with an MSD6AL and Blaster Coil. Oops no help, still the same results. But now with the MSD in I have a better method of checking for spark.

So today, I do one last check of the connections, all the vacuum hoses are in place etc. Start the car, yep again runs just fine. Let it run a bit, turn it off wait start again. But finally it dies. Turns over fine but wont fire, I have my timing light hooked up which is how I'm checking for spark (yes while the car is running the light strobes) and the light will not strobe.
So I then use the method in the MSD manual to check for spark, basically remove the center wire from the distributor cap, un hook by green wire (the MSD green/purple wire) and short it with a jumper. I get spark. But put it back together and no spark.

So from this I would assume that my problem is isolated to the green wire and the distributor. And it is heat/time related.

Does anyone have a clue? The one thing I have NOT done is Gunter's distributor cleaning, I'm going to do this tomorrow.

Car starts runs fine for 5 minutes or so then dies like it has been switched off. What's the last piece of this puzzle?

Thanks in advance.

Jay
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[mca]

Is it possible that your rev limiter relay is bad?

If you pull the fuel gage (left most gage) there is a black box mounted behind it just to the left. On the underside of the box you will find a connection - unplug it and see if it fixes your problem.

I think (not positive though) that if it fails it will kill the spark. On older cars I think it was designed to kill the fuel pump.

Anyhow, it is worth a shot and is an easy test.

[fritzgator]

Happen to have a pic of that relay.83SC

[jtfreels]

Thanks guys. But.... after I read mca's suggestion I started doing some Pelican searching (currently my favorite sport), it appears that the rev limiter cuts power to the fuel pump relay. This would give me no fuel, but not effect the spark. At least that's how I'm reading it. Feel free to correct me. Not to say I won't give this a try. If I weren't at "work" right now I'd run on to the garage and give it a try.

Thanks for the info and the photo. The photo makes me think, would it be nice to have one of those mini TV camera setups to explore the inside of the car better!

Jay

[jtfreels]

A bump and small update for Monday morning.
Started up fine on Sunday after noon, ran for a bit (less than 10 minutes) and uh died..... Yep no spark (checking with the timing light).
So I checked voltage to the 6 pin connector, yep getting 12 volts with the key switched on.
Unplugged the rev limiter, no help. Though oddly when sticking my hand in to unplug this (from inside the trunk) the horn honked slightly, not like I pressed the horn button, softer, but enough for the wife to come out to the garage to check on me.
So no I think about the alarm system, read up on bypassing that, but it appears like the rev limiter the alarm cuts power to the fuel pump relay. I've got fuel but no spark.

So now I think this is related to something inside the distributor. So next step is to take that appart, clean it out and check the magnetic pickup.
Anyone ever had a bad magnetic pickup?

Thanks

Jay

[Gunter]

The dreaded intermittent failure; harder to trace.
Distributor electronic parts are very reliable, the green wire, 6-pin module and coil are the usual suspects.

I know nothing about MSD but the symptoms sound like a failing 6-pin Bosch module.
With MSD, is the 6-pin still used?
Quote:
"The first thing I did was to replace the "green wire" this was very stiff and appeared burned. I had to splice in a connector as the original was one wire.
After doing this the car started easier, but still the same symptoms, cold start fine the quits suddenly."

This is not just one wire, it's 2in1 with the shield being one wire and the core being the other.
When splicing the green wire with the new pigtail, correct polarity has to be observed!
The wire from the distributor to the 6-pin module has an inside (Signal wire to # 7) and an outside (Shield to # 31d)

31/1 = Ground
TD = To Tachometer
31d = Distributor pulse wire shield
A = To positive side of ignition coil
15 = 12V power with ignition ON (from fuse 22?) - 2-pin plug?
7 = Distributor pulse input (Signal wire)

It could also be a failing coil? Bosch black is what you want and maybe someone has an easy way to test the coil? Do NOT test for spark by removing the center cable from the coil and grounding it; VERY BAD!
Bosch warns against this. Use a lead from any plug with a good plug connected to ground when cranking; there should be a visible spark.

Since it is intermittent, can you swap the coil for another one?

To be sure that it isn't fuel-related, you could swap out the red relay temporarily with a black one, replace the 25A fuse #16 making sure it's held tight and the next time it stops running, leave the ignition ON, remove the airfilter and lift the Air Flow Sensor Plate Lever.
Are the injectors squealing?
Meaning: The Air Flow Sensor Contact is working correctly controlling the pump through the pump relay with ignition ON. Bentley page 201-8.

Do you still have the 6-pin CDI module?

[jtfreels]

Gunther,

the problem of the car running briefly then dying was my initial problem. Was having this BEFORE I made any changes (or spent money )

The green wire, purchased the pig tail from Pelican, then made the new wire following Warren's posts, on making this work. I'm pretty confident this is ok, get 675 ohms on the new connection. I think I've read all the green wire posts .
Result car starts fine cold, runs for a while then dies at around 10 minutes

I changed out the CDI box, thinking that it was the culprit, warming up then loosing spark. So I put in the MSD, and a new Blaster coil. (Changed out only the coil first so had the original CDI box and new coil). No change in results with just the new coil, so added in the MSD.

I don't believe, the CDI/MSD or either coil is the problem, as no change in the behavior of the car after changing these.
Result car starts fine cold, runs for a while then dies at around 10 minutes

I'll swear (been doing that alot) that its not fuel related, swapped the relays, injector squeals, frequency valve buzzes when the plate is lifted. While in a period of non start I pulled an injector, got fuel flow. If I attempt a start and it doesn't you can smell fuel etc. I've done these checks based searches.

During a period of non start I can make a spark by shorting out the "green wire" trigger per MSD trouble shooting procedures and that works fine.

So here is my theory. Could it be the magnetic pickup inside the distributor? The one thing I dont remember trying is the continuity check on the green wire during a period of non start. Could the magnetic pickup be cracked or something and after the distributor warms up it fails?
My next step is to clean the distributor and check this (following your procedures).

So is this a plausible theory?

Thanks Jay

[kach22i]

Originally Posted by jtfreels

So here is my theory. Could it be the magnetic pickup inside the distributor?

Yes, unless you have points, then I'd check those too.

You could also check all of your fuses including the fuel relay cap.

[SCWDP911]

Have you been able to take it apart yet Jay? Chuck and I missed you at dinner the other night, but he said he appreciated you going in to make sure the company does not go south in his absence