I have a 350 in my 68RS which recently started to die intermittently when driving. It may happen several times in less than a mile or not happen at all for a week or more. Restarts within seconds. Started dying about a mile from the house. Hood is closed of course while driving. It idles for 25 minutes or more in the garage with the hood open.
It has the Chrysler style electronic ignition with the magnetic reluctor and a Wells amplifier. NAPA coil. All 20 years old and over 50K miles.
Here is what I have tested:
Fuel pump - 6 psi cranking and running. Checked all hoses for cracks and leaks in fuel line.
Vacuum at idle - 15 in. Hg
Coil - 1.8 ohms primary, 8.5 K ohms secondary 9.2 vdc +/- at + terminal even when engine dies
Pickup - 380 ohms. Checked wiring for continuity and to ground - Good.
Ballast resistor 0..5 ohms, 14.3 vdc at input, 9.2 +/- at output even when engine dies.
Checked all wiring between amplifier box and coil and pickup for shorts and open - good
Checked the amplifier box per Chrysler manual for continuity. - good
I am thinking it is the coil, but it restarts quickly which doesn't seem to allow much time for the coil to cool off.
Any thoughts are appreciated before I start throwing parts at it.
Ron

 

Is a ballast resistor commonly used with electronic ignition?

 

Are you seeing a full pump shot of fuel at the carb immediately after it stalls?

Live well,

SJW

 

I think we can agree this is likely ignition given the 'lights out" failure and immediate restart. The Chrysler boxes want between 1.4 & 1.8 ohms coil primary resistance. Ballast should be between .05 & 1.2 ohms. Using an orange or blue box? I would try another box.

Dan

 

If it’s electrical, check your battery cables and ensure they are tight. The coil can exhibit these symptoms as it starts to go bad. Heating up and opening only to read go under no load like an ohmmeter. If it’s fuel related, vapor lock is a possibility as you know. Another possibility is junk in the fuel tank. The pump pulls it up against the sock, the engine stalls and the junk falls away only to be repeated each time you start the engine.

Anyway, best of luck!

 

Red wire syndrome

 

I thought of that, but Ron has been around, I assume he checked the known culprits. The Chrysler ignition is excellent however the blue and orange boxes must be used with a compatible coil and ballast to keep from burning it up. The box is potted in a gel. If you look at its backside and it looks to be melting your box is likely the problem.

Dan

 

The problem got worse after I got a bad load of fuel and had to drain the tank, which is why at first I thought of fuel, but it doesn't sputter upon dying, it is immediate which indicates electrical to me. I had fuel at the carb when it died. The pump is putting out 6 psig. The only thing I noticed is the fuel pressure drops off within 30 seconds or so after shutting down the engine. I took the pressure readings at the carb.
The early Chrysler systems used a ballast resistor. When I put it on years ago, I replaced the resistance wire used on other GM cars with a 0.5 ohm ballast resistor. It checks good as does the coil.
There is no red wire problem on a Camaro and I still have voltage to the ignition when the engine dies. Thus, the ignition switch and power to the ignition is not the problem.
I question the problem of the coil windings opening up when hot, as it restarts within seconds. Not much time to let the coil cool off.
I checked the box and it checked good, but of course that is without voltage applied. I have had problems with these boxes in the past, but it was high RPM miss or complete failure. None self healing. I have had the melted gel problem with a box in a V8 Vega. Engine heat in small spaces.
Am I thinking wrong?
Probably won't get back to it today, so thought I would ask you all for some ideas. I know a couple of you are MoPar owners.
Thanks, Ron

 

Have you considered corrosion on the bulkhead wire connection?

 

Mopar box.. I saw it on brand new mopars on the early 70's...

 

Agree. All it takes is a bad solder joint. Ron, its 2 minutes to change the box ...

Dan

 

Don't overlook the possibility of a frayed, intermittently opening, wire from the coil to the breakerless module, or from the breaker plate to ground. Either one of them could be opening when the vac moves the breaker plate.

Live well,

SJW

 

I was chasing an issue where the car would be running, and then it would just shut off...... like a ghost shut off the key...... it would often start right back up..... I was checking everything, and then one time when I was going to adjust the timing, with the car running, I was putting the wrench on the bolt holding down the distributor clamp and the car stumbled...... I tried again and the car stumbled..... I looked closer and it would stumble when the wrench bumped the distributor wire..... I would bump the wire and the car shut off...... I pulled the distributor and when I inspected the wire, I found that the shielding was partly worn off where it went through the base...... took it all apart, and the shielding came off in that area...... installed new wires, and we were good to go.......

 

Way back when a friend had a brand new 71 or 72 Cuda that the dealer could not diagnose. New technology back then. The car was under warranty.... Finally it broke down at the dealers and the dealer swapped ignition boxes into it ... 2 brand new ones did not work either.. " IF I recall " each colored box designated max RPM limit and " again I think" the chrome box had no limiter in it.... Long time ago... It fixed the problem.... I know it was before 73, because the same guy purchased a brand new 73 corvette....