Are you ready for a real weird one? Random NO spark from a MP electronic ignition system despite numerous parts swapped around...

[turbine68rt]

I know that there isn't any power to be gained from ignition but reliability sure would be good

Call me old fashioned, but the Charger has been running points since '68. Spare NOS points and condenser in the console and I wouldn't be afraid to drive it to California.

 

[BeepBeepRR]

Call me old fashioned, but the Charger has been running points since '68. Spare NOS points and condenser in the console and I wouldn't be afraid to drive it to California.

And you can drive it after China attacks with an EMP...

 

[pnora]

Myself I would lean towards a problem with the distributor pick up. As far a wiring goes you could wire a small LED tight off the positive post of the coil or a cheap LED volt gauge. At least then you could eliminate ballast and wiring.

 

[Cheapsunglasses]

If you are looking into a new distributor, Rick ehernburg sells “better” built “factory” distributors. Comparing it to a cheapy rockauto special his claims might be true. There’s more weight to his, the cap looks and feels like it has more and stronger plastic. The brass terminals are thicker than the cheapy.

Unfortunately I’ve only had a week with it, so I can’t speak for it’s longevity, but just looking and feeling it, it seems like a quality unit

for Mopar Electronic Ignition Distributor RB-Engine Plym Dodge 440/413 Blk Cap | eBay

 

[pnora]

Mancini sells a ready to run that wont break the bank. Pro Series Ready to Run Distributor

 

[turbine68rt]

If you are looking into a new distributor, Rick ehernburg sells “better” built “factory” distributors. Comparing it to a cheapy rockauto special his claims might be true. There’s more weight to his, the cap looks and feels like it has more and stronger plastic. The brass terminals are thicker than the cheapy.

Unfortunately I’ve only had a week with it, so I can’t speak for it’s longevity, but just looking and feeling it, it seems like a quality unit

for Mopar Electronic Ignition Distributor RB-Engine Plym Dodge 440/413 Blk Cap | eBay

These will also accept the fbo limiter plate. Bought 3 of these distributors from Rick for customers and all ran great.

 

[bobsgtx]

Don't take this the wrong way. I don't see any voltage checks when it dies at home. I like to use 30ft. test leads (HF) and a back probe kit (HF) with a multi meter and a test light. I would do voltage checks when it runs and recheck when it won't. I connect the test leads to the battery so I can see a loss in the wiring and ground.

 

[MWbirdLOVER70]

The stock system in my 75 Power Wagon is reliable, so is the one in Jigsaw but both of them have original Mopar built distributors, not aftermarket replicas. This is why I've wondered if the guts in mine here are just ****. I have swapped distributors and had it not fire, then get pissed off and walk away...only to come back in a few minutes and have it start just fine.
I'd embrace an MSD system if I could hide that huge ugly control box. I'd want vacuum advance too. I know that there isn't any power to be gained from ignition but reliability sure would be good.
I'm trying to recall what parts are in place that have been here from 2001 when I converted to electronic ignition.
I've changed every electrical part except the distributor, so to speak. I have pulled this one (During a NO spark episode) to use another, then just to confirm it is bad before tossing it ... I tried it again and it worked.
The same thing has happened with other components. I have had a Chrome ECM for maybe 10-12 years...

View attachment 1633411

The other day during the A/C stuff, after it stalled, I swapped in another ECM and it started.
It is really weird for the car to run fine, sit a few minutes then get no spark upon a restart.
It also is strange to have it sit after a NO start and then just fire up as if nothing was wrong 5 minutes prior without making any more changes.
I could understand a situation where electrical parts got hot and needed to cool down but what about those cold starts after sitting for weeks?
This is really strange.
Sure, I could just keep replacing parts but I want to know what is really causing this. When I change a part and it starts, I thing that it was THAT part to blame but THAT part seems to work in the other cars.

Remember a guy at a show had a bad coil and hit it would short out internally and when cooled it started but you’ve tried that. What about a Petronix kit in another distributor as a cheap test to take the MP whole system out of the equation?

 

[MWbirdLOVER70]

This an interesting idea. Running power to the coil is easy but what about the ECU? It is a 5 pin plug that uses 4 of the pins. Would I need to modify a plug cut from a spare harness?

I forgot to mention....Sometimes during the NO spark, it feels like the engine wants to fire as I rotate the key back to lock. This is why I unplugged the stock one and tried another ignition switch harness....with no change.

I don't think that is it. I have the engine block grounded to the core support, to the firewall too. The battery negative cable goes forward from the trunk mounted battery forward and to the engine block as well.

Could it possibly be a faulty ignition switch?

 

[Bee1971]

I'm fortunate to have a stash of spare parts to test but I want to know how to target the specific problem, not just throw parts at it.
Today during the NO spark, I had power to the positive side of the coil. At one point, both the positive and negative lit up the test light.
No power to the distributor plug.
I pulled the plug off the ECM. See the schematic below:

View attachment 1633399

The wire that they label as "Unused" is green with a red tracer. I do have that and no, no power seems to go to it but....It traces back to terminal L on the middle bulkhead plug on the firewall, then inside to the horn relay. That wire is supposed to dead end but Evans wiring ran it from the ECM plug to the bulkhead connector. That seems wrong. The horn relay should go to the horns, right???

The reason I mention the green wire is because I wondered if somehow the horn relay was back feeding trace voltage to the ECM somehow. I reached under the dash and unplugged it, still NO spark.

Today, I was filling the A/C system with Freon/refrigerant and was almost done when the car stalled and would not start. Yes, again, NO spark. I did the usual test light and ECM swap with no changes. 90 minutes later I sprayed ether down the carb and BOOM, it started.

Green with red tracer would go to or dead end on the 5 OHM resistor side of a dual ballast resistor that was used for the factory 5 pin ECU - On a single ballast resistor it would not go to anything - It definitely should not go back thru the bulkhead connector

The issues you are describing I have seen within the actual 4 pin or 5 pin rubber molding that connects to the ECU - Wiring to the actual female pins - Just because the wiring harness is new or was new doesn’t mean

How is your main factory fusible link

I agree with others on the factory bulkhead connector also that might have resistance

Check out this wire on an Evan’s wire harness that went to the positive side of the coil over the years

I never saw this until I removed the wire insulation . Look at the resistance/heat it caused because of of a bad connection or crimp .

 

[MWbirdLOVER70]

Green with red tracer would go to or dead end on the 5 OHM resistor side of a dual ballast resistor that was used for the factory 5 pin ECU - On a single ballast resistor it would not go to anything - It definitely should not go back thru the bulkhead connector

The issues you are describing I have seen within the actual 4 pin or 5 pin rubber molding that connects to the ECU - Wiring to the actual female pins - Just because the wiring harness is new or was new doesn’t mean

How is your main factory fusible link

I agree with others on the factory bulkhead connector also that might have resistance

Check out this wire on an Evan’s wire harness that went to the positive side of the coil over the years

I never saw this until I removed the wire insulation . Look at the resistance/heat it caused because of of a bad connection or crimp .

View attachment 1633513Dammmmmmm

 

[68_661charger]

My 69 with MP ignition used to do that, produce no spark intermittently. Its been a long time ago and this might not make sense, but I remember pushing on the one bolted on wire on the alternator hard enough to turn the post in the alternator slightly and the car would start. Like I said, its been a long time and I might be thinking of another problem but try it just for laughs.

 

[68BabyBlue]

Call me old fashioned, but the Charger has been running points since '68. Spare NOS points and condenser in the console and I wouldn't be afraid to drive it to California.

Same with my GTX. I had a nearly identical, factory original '69 with points ignition in the 90s, and drove it for seven years with zero starting issues. I ran my '66 Imperial with points ignition for 50,000 miles during the same period, and had the same reliability.

 

[Black_Sheep]

I had intermittent no spark years ago and it turned out to be an internal break in a wire on the pickup coil. I found it by connecting an ohm meter to the leads on the pickup coil and flexing the wires.

 

[RemCharger]

Not as familiar with a 70, but they get power from the yellow start relay to the ballast?

 

[turbine68rt]

Same with my GTX. I had a nearly identical, factory original '69 with points ignition in the 90s, and drove it for seven years with zero starting issues. I ran my '66 Imperial with points ignition for 50,000 miles during the same period, and had the same reliability.

I totally get switching to EI to virtually eliminate periodic maintenance. I did it with a daily driver '66 Coronet for 10 years, but there's something very satisfying about getting a 50+ year old car to run and perform great using such a "crude" method by comparison to modern standards. I have a timeslip from the early 90's running a 14.20 in totally showroom trim. That's when I could finally get it to hook up with bias-ply redlines.

 

[Belvedere408]

I had similar issues on my 67 B. It stemmed from bad bulk head wiring. Was causing me to lose coils and distributors. The coils would get really hot and stop working, let it sit an hour then perfect.

 

[Dennis H]

I too just jiggle/put a little gentle torque on the Bulkhead Connector.

 

[Under Pressure]

May not be of any help but 6-7 years ago I was chasing a very similar gremlin with my 70 GTX, and for me it turned out that when I wiggled the large white flat multiple wire harness under my dash (above my right leg) the car would fire, after a couple times of this, I found some connections in the plug that looked ugly and discolored.
I replaced and re-wired and all of them and all good since.
I am not great with electrical and hate it,
Just a guess

 

[68-500]

With the trunk mounted battery? Did you run the negative cable all the way to the engine block? And what size cable? The longer run I would want a 1/0 for sure to eliminate voltage drop. Im leaning toward making sure every cable termination is tip top. Then start on every body ground per fsm and everything that may have added over the half century.
You mention it seems like it might want to start when you let off the key. Id look at the ingnition switch.
I know your invested in electronic ignition. But a dual point prestolite might be in my future.