Intermittent stall/crank no start.

[beanhead]

It's hot in the garage. Hoping for some ideas with this to save some sweatin'...

'68 Plymouth converted to electronic ignition years ago, FBO ECU, matching Pertronix coil, no ballast. Box mounts on the inside of the firewall, behind the glove box area. All components well grounded.
Firecore/Summit distributor. Alternator replaced about 3 years ago with a Napa unit.

3 times in the last month now my car has quit running during driving. I'll pull away from a light, it quits, diesels for a second like it wants to re-fire, but then dies...and I'm on the side of the road. It will crank over just fine but won't start. Each time I have swapped the coil and box and by the time I'm done futzing with that stuff, it has started and I've been able to get home.
However...It's done this with two separate boxes (one a new FBO) and different coils. It did it with a previous distributor and also a newer one---Same exact problem leads me to believe those parts aren't the root cause.

This was interesting--the last time it happened, after I got it started again, I noticed the ammeter needle sitting halfway between center and "C" and it stayed like that for the whole 3 mile ride home. Never seen it stay there that long before (even after sitting for a month) and if it happened the previous times I didn't notice it.

Come back out the next day; all is fine. Put the ECU and coil back in that were in it when the failure happened; all is fine. Never had any issues like this previously with this car. WTF.

I suspected my 20-year-old VR706 regulator so I replaced that last week. Since then I've driven it 3-4 times and no problems...so far.
I've checked all the wiring, looks okay. No 'opens' or shorts to ground when wiggling the associated wiring at various points.
It's gotta be in the ignition circuit, not start circuit or it wouldn't turn over, so I don't suspect the battery/connections unless someone has a different idea.
Ignition switch contacts? It's still the original.
There's always fuel in the carb bowls so I don't suspect fueling issue?

I realize it's near impossible to nail these things down over the 'net so I'm really just looking for anything I could test for if it happens again, voltage checks etc... Thanks

 

[blue69runner]

Have you replaced the start run relay. Just might be something that simple. With my car it had been starting ok but last week. Hit the key and nothing happened. Tried again and it started. This happened again. So took my wires off and cleaned them and every thing is fine now.

 

[beanhead]

Have you replaced the start run relay. Just might be something that simple. With my car it had been starting ok but last week. Hit the key and nothing happened. Tried again and it started. This happened again. So took my wires off and cleaned them and every thing is fine now.

The car will turn over fast n' furious with the key....just won't fire. This tells me the relay is okay.
Thanks for the input

 

[blue69runner]

Had a new coil on the motor and it work since April but the other day it did not want to crank. Got a new coil and it started right up. Fire on the one I replaced was showing orange fire. Bummer. So took it back and they refunded my money. The product's we get now day's just are not like we got year's ago. LOL.

 

[Under Pressure]

Was chasing this EXACT gremlin this month, I would get 5-7 miles and then just shut off, then crank rapidly (indicating no spark)
Cool down completely and fire right up.
After searching some old threads on this site (you can sure learn a lot from them) I figured after a new coil, it had to be the old orange box.
I contacted a great supplier on this site, HALIFAX, I he had NORS blue boxes, I bought 2 (need a spare) got them in 3 days.
Gave the car a long hot run and so far she’s good
Ps, never hurts to also have a ground strap to the block

 

[HALIFAXHOPS]

Thanks for the plug. It can be the pick up coil in the distributor also going out they act up like that, fail hot and when they cool down they are fine. PIA to trouble shoot it.

 

[Outlawd]

Keep it simple, check and recheck all grounded electrical ignition parts. How about the key switch and wire terminals on it loose? simple crap happens and easy to check.

 

[beanhead]

Thanks for the plug. It can be the pick up coil in the distributor also going out they act up like that, fail hot and when they cool down they are fine. PIA to trouble shoot it.

If it happens again, could I test the pickup without pulling the distributor, Maybe by connecting my test leads to the two pickup wire terminals in the ECU harness and crank the engine? If that's a valid test what reading would I be looking for?
It's done it with a previous as well as a new distributor but we all know new doesn't mean good!

Keep it simple, check and recheck all grounded electrical ignition parts. How about the key switch and wire terminals on it loose? simple crap happens and easy to check.

I have not ruled out the switch...it's been a suspect in my mind though as I *think* it's the factory installed unit. I know for sure it's at least 21+ years old because I've never changed it.

View attachment 1129763 Was chasing this EXACT gremlin this month, I would get 5-7 miles and then just shut off, then crank rapidly (indicating no spark)
Cool down completely and fire right up.
After searching some old threads on this site (you can sure learn a lot from them) I figured after a new coil, it had to be the old orange box.
I contacted a great supplier on this site, HALIFAX, I he had NORS blue boxes, I bought 2 (need a spare) got them in 3 days.
Gave the car a long hot run and so far she’s good
Ps, never hurts to also have a ground strap to the block

I've experienced the problem with a couple different boxes; the FBO box and a spare good USA-made Chrome Mopar one. The engine has a ground at the firewall and one in the battery negative terminal that attaches to the radiator support up front. The ECU, regulator, and distributor all have good connection to ground as well. I hear ya, weird intermittent problems usually do turn out to be grounding issues...but I haven't found a weakness there yet.

 

[beanhead]

Thanks for the feedback everyone!

 

[HALIFAXHOPS]

I forgot the actual but if it is 0 ohms hot it is failing, test it cold first to see what it is then run it hot till it fails and read it again it should be close to the original reading, if 0 time to get one (find a older one the new ones suck)

 

[beanhead]

I forgot the actual but if it is 0 ohms hot it is failing, test it colld first to see what it is then run it hot till it fails and read it again it should be close to the original reading, if 0 time to get one (find a oder one the new ones suck)

Excellent idea getting a "when it's working" reading to compare to...thanks Ray!

 

[moparedtn]

I know I keep bringing it up....but I wonder if those of us running electronic that are also removing
the ballast aren't prematurely frying ignition coils in doing so?

 

[beanhead]

I know I keep bringing it up....but I wonder if those of us running electronic that are also removing
the ballast aren't prematurely frying ignition coils in doing so?

You sure could, but the Flamethrower coil is directed to not be used with an external resistor. (The instructions with the ECU say the same thing--no ballast resistor).

 

[moparedtn]

You sure could, but the Flamethrower coil is directed to not be used with an external resistor. (The instructions with the ECU say the same thing--no ballast resistor).

I know the "kits" out there come with a 1.25 ohm ballast and some of the MSD Blaster coils say to use a 0.8 ohm
when using the factory ignition, so I get confused on which is more important not to potentially damage with
the "wrong" ballast - the control unit or the coil?

 

[HALIFAXHOPS]

Contro unit really needs it matched.
FYI

 

[moparedtn]

Contro unit really needs it matched.
FYI
View attachment 1130195

Thanks as always Double H - I have the 0.8ohm one on Fred right now but looking at that chart
(as I have the other times you've posted it), I still can't come to a conclusion really.
I mean, it's all over the place according to what ECU is on the car (and I don't see a listing for
"old orange box from the 80's" categorized on it ).
I have made it a point to feel the MSD Blaster 2 after a couple local trips and the rascal has been
pretty darn warm, almost to the point of being too hot to touch. I don't know if that's normal or
if it means it wants a different ballast (higher or lower rating even?).

 

[HALIFAXHOPS]

This help?

 

[blue69runner]

Like I said before just go to summit and pay 145 for the new distributor electronic type and all the other stuff come's with it. Save a lot of head aches.

 

[tommyg29]

I have a similar issue. Havent tried starting in about 6 months. It cranks and cranks, but no fire. Tried starter fluid...nothing, so I figure it has to be electrical. I have a 72 with a stock type system including the orange box and ballast but also a flamethrower coil.
How do I test the coil?

 

[beanhead]

Okay I'm updating this thread:

It cooled down to 95° tonight so I went to take the car out for a little evening spin.
-It started up great and ran for about one minute, then died.

-The ammeter read slightly high for the first maybe 20-30 seconds, then moved back toward the center mark. That's normal for my car when it hasn't been fired up in a few days.

-Since it was kind enough to die in the driveway this time I clicked the key to 'Run' and checked some voltages. (FYI my good meter is at work so I was testing with my Fluke T-600 which does not show tenths of a volt.)
13 at coil positive
13 at battery and alternator output terminal
13 at ignition terminal of voltage regulator
During cranking/no start I got the same resistance readings on distributor pickup wires at ECU as I did when car was starting okay. (Red light on ECU flashed during cranking which also indicates signal from distributor with this ECU).

Both carburetor bowls were filled to the proper level.

After scratching my head for a minute, I attempted to start it.....fired right up. So it was only dead for about 3 minutes.
While it was idling I wiggled the wiring at the ECU, along the firewall, and at the bulkhead...no effect.

-I hit the road and saw that the ammeter needle was back between center and 'C', but this time stayed there for most of my drive--5 minutes maybe. Just like after previous 'no start' incident.
I'm thinking that means something.... When the car runs normally as I said before the ammeter needle will show a slight charge for less than a minute; by the time I'm out of the driveway the needle is riding the center mark. After this problem occurs the ammeter shows a high state of charge for much longer than normal.
Alternator or battery problem? Maybe but that doesn't seem like it would cause my sudden and temporary no-start I don't know. This is getting interesting!