Lost Spark during rebuilt engine break-in

[KyleB.]

 :help:Not too sure what happened.
This has been a year long project involving engine rebuild, interior restoration etc.
12 minutes into the break-in procedure, the engine just shut off, as if I turned off the ignition.
I pulled a spark plug and cranked the engine with a remote switch, I had intermittent spark, then nothing at all.
Same scenario when using ignition switch.
Replaced Cap, Coil, Rotor, and Wires....Plugs were new.
I have 5.43 Volts at the yellow wire on the coil. Can't seem to find what it should really be in my Chilton's.
I checked the two ground wires on the firewall, cleaned them up, seems like a good connection/continuity to battery ground.
What am I missing

Rewind 12 hrs.
While cranking engine with remote switch at the solenoid, (had dist. wire off of the coil cause I didn't want it to start yet) I noticed the coil trying to arc to the block/coil bracket. That didn't seem normal so I started troubleshooting for a ground short.  I hand-over-handed every wire in the engine bay.  I didn't find anything strange except for the red wire (described as a 35 ohm resistance wire on the schematic) gets pretty warm to the touch.  Resistor = warm, so I don't think it is a problem....I don't know for sure though.

This the only thing keeping me from goin for a long awaited Sunday drive

[Draekon]

Voltage to the coil should be right around 6V, which you are basically at.

Maybe your ignition module decided to die.

[ammachine390]

The black wire going into the distributor base is an ignition system ground. I believe it just screws into the block or distributor base. Either way, if it has a bad connection, you'll have no spark.

[KyleB.]

Voltage to the coil should be right around 6V, which you are basically at.

Maybe your ignition module decided to die.

Is there a way to trouble-shoot the ignition module?

[KyleB.]

The black wire going into the distributor base is an ignition system ground. I believe it just screws into the block or distributor base. Either way, if it has a bad connection, you'll have no spark.

Does it ground through one of the screws that secures the pick-up module? Can't find anything going to the block from the dizzy. 

[ammachine390]

It goes from the ignition module into the distributor. At the base of the distributor you should see 3 wires coming out, a purple, orange and black. The black grounds the ignition module.

[KyleB.]

Would it be reasonable to think I could hook up a temporary jumper from the dist. base to ground?
Or do I need to go off of that black wire exclusively?

This has to be something simple. Seems like it always is.

[eaglefreek]

How long did you crank it with the coil wire disconnected? The coil will try to find a ground with the coil wire off. It isn't good for the coil when you do that. It can overheat and damage the coil. Your best bet is to pull the power supply to the coil if you need to crank the engine and don't want it to start. Also make sure there aren't any wires that may have got damaged during the engine install that may be grounding out.

[ammachine390]

Would it be reasonable to think I could hook up a temporary jumper from the dist. base to ground?
Or do I need to go off of that black wire exclusively?

This has to be something simple. Seems like it always is.

I don't think so because whatever that wire screws into is most likely still a ground. Providing this is the problem, its just that the wire is not connecting to it. You could put a jumper from a good ground the the actual wire though.  

I would just remove the dist. cap, and check the connection. It's easy and free. I think there known for corroding and causing no spark conditions. I believe some members have tapped another wire into the black wire and run it straight to the negative battery terminal.

Also, take a look at this.
http://forums.amceaglenest.com/index.php?topic=35631.0

[KyleB.]

Ground continuity from dist. housing to battery is SAT @ .001 ohms.
I disconnected and ran cont. test from ground pin in the connector (dist. side)=.001 good.
Did same for ICM and got 435 ohms.  It must use the dist as a ground.

The part that has me puzzled is that it ran for a while then lost spark.  Are there any fusable links in the spark circuit?

Thanks for all the help up to this point.  I am going back and forth to the shop to try your suggested trouble-shoots.  Good times 

[ammachine390]

Ok, it seems like the ground connection is not the problem then. I believe the parts stores can test the ICMs.

[KyleB.]

Worse yet.
For whatever reason, it just started.
Wonder when it will decide to not start again???
I better get the ICM tested.

Thanks for going through that head scratcher with me.
I don't feel real good about it running since I never found a "Smoking Gun"

I gotta get it to quite dying in gear with the brakes on now!!
Any tips for that one??

[Smitch]

The ICM should supply 12 volts to the coil when the ignition switch is in the start position until the engine starts then switch and run through the resistor wire supplying 6 volts in the run position. The ICM needs to see around 3 ohms resistance in run, IIRC.
Try running extra ground cables from the block to the firewall and the inner fender(s) to resolve the "dying in gear with the brakes on now!!".

[Jurjen]

The ICM needs to see around 3 ohms resistance in run, IIRC.

That's correct 1.35 Ohm from the resistor wire and 1.35 Ohm from the coil itself (together 2.7 Ohm).

Do you have ported vacuum to the distributor?

[GRONK]

You should only have ported vac to the distributor when running the carter bbd if you have already done the ECM Test bypass.  Otherwise you should have manifold vac to the dizzy.

Sounds like electrical to me.  I agree if the engine was cranking w/ the coil arching out to the block you might need to replace the coil.  The Duraspark II ICM is pretty bulletproof.  I would look at coil/wiring before replacing the ICM.  A simple way to eliminate all guessing and save trouble shooting time would be to drop a $100 HEI in place and regap the plugs.  i spent several weekends troublshooting one of my CJ's and gave up.  15 minite install of an HEI and I was on the road.

not saying give up, but time=$$$ and with the HEI only costing $100 IT'S DEFINITELY WORTH IT.