Sudden loss of spark - JeepForum.com
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post #1 of 38 Old 07-17-2019, 02:38 PM Thread Starter
shok47
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Sudden loss of spark

Hi,

have a 1983 CJ7 4.2L 258 inline 6 with a Holley 2 BBL. Looks like I have the Nutter Bypass but have to double check since its been awhile. Do have some vacuum lines plugged, and charcoal canister no longer exists.

Its been over 8 years since I had this baby on the road. I parked it where it sat. About 6 months ago, I started it with a fuel bottle and it started and idled like when I parked it. Drove it around the yard etc.

Yesterday I decided to get it going for good. I bought a new battery and ran the fuel like into the fuel bottle. It started as it always did, of course went through some cranking and 5-6 starting fluid blips before actually started. Drove towards the garage. Turned off and went to eat. Came out started it, moved it a little then it died and stopped starting/sparking.

I remember having her die one time just driving and wasn't able to start it. If I recall correctly, it was something near the wiring harness at the driver side firewall. Something real simple. Any ideas regarding this spot?

Here is what I have done so far:

Several attempts of starter fluid in the carb had no effects at all.

Pulled a spark plug boot and put another spark plug on and rested it on a bolt that was sticking out of the fender for ground and cranked it to check for spark. NADA.

Pulled the wire from new (at the time, 8 years ago) MSD ignition coil that goes to the Distributor cap (also new at the time, including the internals). Ran a wire from the NEG terminal to the boot. Cranked the engine to check for spark. NADA.

Checked the power going to the + and - Ignition coil leads with ignition switch on. Showed 12v on the +. The - showed power and believe it did pulse as I saw the voltage drop once or twice (will use the light bulb method next to confirm)

I stopped there because I pushed it in the garage and the gas fumes was getting strong.

Next task: take out the Ignition Control Module and get it tested at Autozone?


From research, some had said the ignition switch was causing no spark. I did have issue with the ignition switch once but dont remember if I replaced it or the issue went away. The Ignition switch would get stuck on cranking and I had to disconnect the battery to stop. Hasn't done that since the recent starts. Also I don't need a key to turn it so I feel like it might be the old one, so I wanted to note that.


What do you guys think?



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post #2 of 38 Old 07-17-2019, 03:36 PM
Matt1981CJ7
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I'd check the resistance on the primary and secondary sides of the coil and see how it matches up to MSD's specs. Then check the resistance on the pickup In the distributor. Should be around 600 ohms.

What ICM are you running? Is there any visible goo oozing from the bottom side of it?

Matt


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post #3 of 38 Old 07-17-2019, 03:58 PM Thread Starter
shok47
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Hi Matt,

I never touched it so I believe I have the stock one. Will get to check it out tomorrow or Friday and report back with the MSD Ignition coil resistance test


Thanks


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post #4 of 38 Old 07-17-2019, 04:06 PM
LumpyGrits
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Cj

Are you still using that POS, OEM horseshoe connector on the coil?
Try this-Run a jumper wire from the battery POS(+) to the coil POS(+) and see if it will now start.
LG

Have'n you along, is like loose'n 2 good men
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post #5 of 38 Old 07-17-2019, 04:18 PM Thread Starter
shok47
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Quote:
Originally Posted by LumpyGrits View Post
Are you still using that POS, OEM horseshoe connector on the coil?
Try this-Run a jumper wire from the battery POS(+) to the coil POS(+) and see if it will now start.
LG

Looks like I cut those off and installed ring connectors with the MSD ignition coil. I will be redoing those as I see some oxidation on there. I did take them off and wire brush the terminals a bit to see if it made a difference. Nope

Thanks


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post #6 of 38 Old 07-17-2019, 04:18 PM Thread Starter
shok47
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Quote:
Originally Posted by LumpyGrits View Post
Are you still using that POS, OEM horseshoe connector on the coil?
Try this-Run a jumper wire from the battery POS(+) to the coil POS(+) and see if it will now start.
LG

Looks like I cut those off and installed ring connectors with the MSD ignition coil. I will be redoing those as I see some oxidation on there. I did take them off and wire brush the terminals a bit to see if it made a difference. Nope


I dont remember if there is a fuse under the dash I should be checking. Is there?


Also when I mentioned ignition switch, I was referring to the ignition lock tumbler

Thanks


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post #7 of 38 Old 07-17-2019, 05:38 PM
LumpyGrits
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Cj

Then try the jumper from the battery to the coil.........
LG

Have'n you along, is like loose'n 2 good men
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post #8 of 38 Old 07-17-2019, 05:54 PM Thread Starter
shok47
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Quote:
Originally Posted by LumpyGrits View Post
Then try the jumper from the battery to the coil.........
LG

Yup, forgot to say, will get to that in next few days


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post #9 of 38 Old 07-17-2019, 08:14 PM
BagusJeep
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If you have 12V at the coil in RUN, you are missing the ballast resistor. If the coil is designed for a ballast i.e. it runs at 7V normally, you will get issues. The coil and module will both overheat. The ballast resistor was a length of resistor wire soldered and heat shrunk into the wire that feeds the +ve side, they often burn out but you can replace with a small ceramic block resistor or another length of the same wire, but they get hot so do not bind into the wiring loom with other wires.

Also, if you leave the ignition in RUN without running the engine, say fiddling with the wipers, it will run amperage through the module to ground and slowly cook the module until the potting compound oozes out the back. This is a feature of Duraspark!!

If you have 12V at the coil in START and a signal from the module on the -ve side, your no spark is in the coil area.

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post #10 of 38 Old 07-18-2019, 09:28 AM Thread Starter
shok47
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Quote:
Originally Posted by BagusJeep View Post
If you have 12V at the coil in RUN, you are missing the ballast resistor. If the coil is designed for a ballast i.e. it runs at 7V normally, you will get issues. The coil and module will both overheat. The ballast resistor was a length of resistor wire soldered and heat shrunk into the wire that feeds the +ve side, they often burn out but you can replace with a small ceramic block resistor or another length of the same wire, but they get hot so do not bind into the wiring loom with other wires.

Also, if you leave the ignition in RUN without running the engine, say fiddling with the wipers, it will run amperage through the module to ground and slowly cook the module until the potting compound oozes out the back. This is a feature of Duraspark!!

If you have 12V at the coil in START and a signal from the module on the -ve side, your no spark is in the coil area.
I will have to check which ICM I have. Which ICM do people prefer? Is it all interchangeable/ plug and play? I have read that some dont need a ballasts?


Thanks
Thanks


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post #11 of 38 Old 07-18-2019, 10:30 AM
Matt1981CJ7
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The OEM Ford modules are the best, but good luck finding a NOS one. Most of the cheap replacements aren't worth installing. Most guys either upgrade to a MSD module, or they go HEI.

But, I don't think the module is your problem. A failing ICM will usually give you warning signs, like:

1. Engine will start fine when cold, then suddenly die when hot.

2. Engine will fire in the "Start" key position, but will die in the "Run" position.

3. Engine won't fire in the "Start" position, but will attempt to fire when you release the key to the "Run" position.

Matt


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post #12 of 38 Old 07-20-2019, 01:36 PM Thread Starter
shok47
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Havent gotten to testing but grabbed some pics. I have the motorcraft 12A199. Here is pic. Is that hole suppose to have black stuff or did i fry it like mentioned?

Looks like i have the Nutter Bypass. Made a video of it.

https://youtu.be/KEbMvdUkBzc
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post #13 of 38 Old 07-20-2019, 04:52 PM
jumbojeepman
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1st I'd check for power at the coil. 2nd, a hallmark of a module failing when the engine is running is it letting out a huge backfire followed by the engine no longer running. Since you didn't mention this, I would move to the third thing, which would be the pick-up coil in the distributor.
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post #14 of 38 Old 07-21-2019, 10:14 AM
lebowski94
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That is a quality module you have there and you cannot tell if they have failed just by appearance.

Here's what you gotta do, Check for 8-12 dc volts at the coil while someone is cranking it and with the key just left in "RUN" position.

Then check PICK UP coil inside distributor for resistance, you will need to google a diagram of the distributor to find out which leads connect to the pickup. Easy. Should be a few hundred ohms me thinks, definitely not 0 ohm or infinite ohm.

Also, measure the resistance of your coil with all of its wires Disconnected! Should be about 10K ohm primary to secondary and about 1.5 ohm across both primaries.

The duraspark is a great ignition and having a issue is par for the course after 35 years.
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post #15 of 38 Old 07-21-2019, 03:03 PM Thread Starter
shok47
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I redid the ring terminal.
Testing the resistance with all wires disconnected, for the MSD BLASTER 2 coil. Primary at .6 to .7 secondary at 5.45

SPEC for it are:
Primary resistance: .7 OHMs
Secondary resistance: 4.5K OHMs

Reconnected wires. Went to battery NEG and POS in ignition coil. When key is turned, goes to 11.4-12v.
with POS and NEG on the POS and NEG coil, they all show 11.4v - 12v.

When cranking, no voltage change

Thanks


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