Driving the D150 today, got about 60 miles out of Indy and the truck basically shut off.
I was able to coast into a near by gas station and parked. Looked under the hood checked for loose wires, confirmed the fuel delivery was ok. The truck would crank and about 1 in 5 times would start and run for maybe 10 seconds.
Just as I was about to give up, gave the starter one more hit and the motor caught and kept running.
Drove another 20 miles and got with in a mile of my destination, then as before, the motor shut down.

Figuring it was the HEI module, got a ride to and from a near by AZ.
Swapped in the new module and absolutely no change.

Got the truck towed to where I could work on it and have borrowed transportation.
When out and bought a new GM style e coil from O Reilly, installed that and again absolutely no change

I have a spare rebuilt slant distributor in the trucks part stash.
Swapped that in and again still no start.
Yes, the rotor spins when the engine is cranked.

Checking voltage at the upper most lower pin set and I get 11.5 volts or so with the ignition switched on, but not cranking.
Checking the voltage at the same terminal, during cranking I see 9.5 volts.

I have also checked the HEI module ground, the continuity of the harness that connects the upper two module terminals…

I called Charlie S and was discussing the issue with him and he had me checking the voltage of the lower module terminal with the ignition on,, the motor still not running, in about 5 minutes the coil, and this is the new coil, got so hot it started smoking, got hot enough the bottom of the coil case bulged out and it split its innards.

So what the heck is going on? An ignition system that has ran fine for nearly 50,000 miles and nearly 10 years,, now won’t spark and is cooking coils.

Any trouble shooting ideas appreciated.

Charlie recommend that I buy a test lamp and see if the non power bottom tab is ‘switching on and off’
I bought a test lamp this evening, will check the switching tomorrow.
I also went in search of a replacement HEI module for the new one I bought this AM,
None at Advance Auto, none at O Rieley
Back to AZ and bought the last one they had. They had two this morning. Now they have none.

I will be going back into this HEI quandary tomorrow.

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Doo Ron Ron and the Duke of Earl are friends of mine.....
https://www.youtube.com/watch?v=uX8Nj8ABEI8

Is this a clue to something going on?

Or is it normal condition of "key on, engine off" situation?

And have you looked at a spark plugs/ and the spare distributor had it's own distributor cap? No ides as to why or how they are part of the problem, but not wanting to overlook anything ether.

Hey John, the only time I have seen a coil do that was when I left my ignition switch on in the race car with it not running. My low oil pressure cut off was shorted/ grounded since it had no oil pressure and the coil over heated and blowed up. This short was not enough to blow the fusible link either. The hot wire to the coil ties in to a lot of stuff if I remember correctly. Alternator, voltage regulator, …etc.

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2 Mopars come with Spark plug tubes. One is a world class, racing machine. The other is a 426 CI. boat anchor!

12.70 @ 104.6

An update

Since the new coil that I purchased smoked and blew the bottom out after approximately 5 to six minutes of setting with the ignition on and the motor not running, swapped the coil that I was running, a MSD E coil back in. Went looking for a second replacement HEI module, thinking the AZ one purchased and installed as bad out of the box. Neither Advance or O Reiley had one, back to AZ and they had one more, so I purchased it. Installed and again, no spark.

Checked continuity on the coil + and - wires from the HEI terminal connectors to the coil three way connector, that was good. Checked continuity from the distributor connector to the top two terminal connectors at the HEI module, that also was good.

With the ignition on and the motor not running checked voltage at the HEI B and C terminals, from memory the B is the power in and the coil + wire, the C is the coil negative wire.
Got 11.5 volts at the coil + and 3.5 at the coil -.

Spoke on the phone with Charlie S. Charlie has a Diplomat with an HEI conversion, on his car also with the ignition on and the motor not running, he also got 11.5 at the B power in terminal and the same 11.5 voltage at the B or coil negative terminal.

That is much different from what I am seeing. I put the HEI module that failed back in got the same 11.5 at the B and about 3.5 at the C, put the second AZ HEI module back in and again got the same 11.5 and 3.5 voltage reading at B and C respectively.

So did I have an HEI module fail, then buy two more HEI modules that new, exhibit the same failure mode? Or maybe the existing coil has gone bad and is cooking the HEI modules somehow, nearly instantly? I really don't know.

I borrowed a vehicle, and I am back in Indy now, I plan to get another set of coils and HEI modules together, along with a points distributor, a points coil and bracket and a resister block and head back out to where the D150 is parked probably mid next week. I will try going through the HEI swaps again, if that does not work out, I will install a points system to get the D150 running and back home.

Any ideas on how to bench test an e coil, this one has three pins, + tach out - in that order.

and I changed distributor caps when I changed distributor caps when I changed distributors.

and I did some google searches on hot-warm coils with the ignition on and the engine off. In that condition, apparently one can smoke a coil, 5 to 6 minutes seems really quick though.

thanks

_________________
Doo Ron Ron and the Duke of Earl are friends of mine.....
https://www.youtube.com/watch?v=uX8Nj8ABEI8

Very detailed, thanks John. Personally, I would swap in a stock coil with the appropriate ballast resistor for that coil, and try again. It really smells (haha) like an internal problem with the coil(s).

I have never run HEI but only helped people wire them up, so I have very little experience with that system.

Lou

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Home of Slant6-powered fun machines

Bizarre conditions there.

I have had a few hiccupps with the HEI swaps but nothing as severe as what you are going through.
sure does seem odd that you have gotten many miles and years of trouble free service, then boom, burn..

Good luck in getting it sorted.

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http://www.youtube.com/hyperpack

John, just thinking. Disconnect the (-) wire from the module. Turn on the ign, (engine off) and check voltage at the module (+) should be approx battery voltage. Now check the voltage on the disconnected wire that went to the module(-). See if that has battery voltage, or is the 3.5 volts. If battery voltage I still say bad module. If 3.5 volts probably internal short in the coil.

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Charrlie_S
65 Valiant 100 2dr post 170 turbo
66 Valiant Signet 225 nitrous
64 Valiant Signet
64 Valiant 4dr 170

Charlie,,
thanks that is a fine suggestion,, and I will try that,, problem is, I am back in Indy, planning to getting Greenville OH, where the D150 is will be late next week.

_________________
Doo Ron Ron and the Duke of Earl are friends of mine.....
https://www.youtube.com/watch?v=uX8Nj8ABEI8

Do you have anything else, like a tachometer, wired to the negative terminal of the coil? A correctly functioning HEI module should not ground the coil unless it receives an RPM input, but it may not be the only thing connected to the negative terminal. So you'll want to check anything else that may be wired there as a possible rogue ground - including damaged wiring.

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Matt Cramer
1966 Dodge Dart turbo / EFI project

There is a tach on the truck. Using the GM E coil, there is a dedicated coil terminal for the tach coil negative connection.
The coils pins are: positive, tach signal ground, negative in that order.
Disconnecting the tach wire at the coil is something that I can try when I am back to the truck.

When the D150 was starting and running properly, I would see the tach needle jump just a bit when the starter was engaged, and the engine was turning over.
In its current no start condition the tach needle lies flat and does not move at all with the starter engages and the engine turning over.

_________________
Doo Ron Ron and the Duke of Earl are friends of mine.....
https://www.youtube.com/watch?v=uX8Nj8ABEI8

The 83 D150 is back home and starting - running fine.

I set up a bench test where I wired up a coil and hei module.
Using alligator clip test leads:
* 12 v power to the coil +
* jumper from the coil + to the HEI B terminal
* check voltage at the coil - and the HEI C terminal.

using the two spare coils and two spare HEI modules that I had at home, with all combinations the coil negative would have battery voltage , 12 volts and the HEI C terminal would have no voltage.
Jumper the coil - to the C terminal and the C terminal would have battery voltage.
This simulates the voltage condition at the coil and HEI module with the ignition on and the engine not running.
This test was built upon Charlie's comment that the B and C terminals of the HEI need to show battery voltage with the ignition on and the engine not running.

The 12 v at the B and C terminals is different from what I was measuring on the D150. With the ignition on and the engine not running I would get 10 or so v at B and 3.5 v or so at C.

I drove out to where the D150 was and did the bench tests with the HEI module and the coil that was on the truck when it quit running, the coil that got smoked and the two new HEI modules that I purchased from AZ. All combinations had 12 v at the B terminal and 12 v at the coil negative wire. With no voltage leak through to the HEI ground or the coil case.

That left one possibility. The one that Matt C had mentioned. The dedicated tach wire off the coil was grounding. These GM E coils had three pins. Positive, Tach out and Negative.
I installed a GM coil that I had gotten from a pull a part years ago, the AC Delco HEI module that was in the D150 when it quit running. Disabled the tach out wire at the coil.
With the ignition on and the engine not running, had 12v at the B and C terminals.

And the D150 started. Ran fine the nearly 2 hours back home.

I did learn a lot about HEI voltages through this exercise. The question remains, why did the tach out wire go to ground?
Along with a Sunpro tachometer I have a shift light connected to that wire. Both the tack and the shift light have been on the D150 for the past 10 years.
I will dig into that and post what I find.

thanks for the troubleshooting ideas and support.

_________________
Doo Ron Ron and the Duke of Earl are friends of mine.....
https://www.youtube.com/watch?v=uX8Nj8ABEI8

Glad to hear you sorted it out, John! Happy Slanted motoring...

Lou

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Home of Slant6-powered fun machines

Good Report.

Seems like some faulty tach connection in the engine compartment, under the dash or through the firewall.. or somehow is grounding in the tach itself.


Greg

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http://www.youtube.com/hyperpack

Good deal John!

Tachs do weird stuff sometimes. I had an old Stewart-Warner that would go crazy only with the lights on. The light had lost ground internally and was grounding through the tach circuit......

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Official Cookie and Mater Tormentor.