CJ3A Direct Short Battery to Block: Ignition Issues

[bmorgil]

i n preparation for swapping out the distributor. I tried to start the Jeep one last time with the electronic ignition using your suggestion of running a jumper from positive battery to the positive post on the coil and EUREKA! I started seeing spark right away and before I could turn it off the engine started on three cylinders. After letting it idle for a moment, I turned it off and tried to restart with no luck. However, when I put the jumper on, it fired up again.

Since then, I've removed the jumper and started it several times with no problem. I'm using the same gage of wire on the jumper that I have going to and from the ignition switch.

Larry, he got it to run with a jumper to the coil and the electronic distributor. I think he is saying he is back to no spark with the jumper off and using the key again?

Clarify that for us Chris.

[CChris]

Larry, he got it to run with a jumper to the coil and the electronic distributor. I think he is saying he is back to no spark with the jumper off and using the key again?

Clarify that for us Chris.

Good Morning,

Since my the unfortunate incident where I shorted the starter + post to the block while changing out my defective foot pedal actuated 6V starter. I have installed a new, solenoid operated 12V starter, and replaced the following with new components:

1) Negative and Positive battery cable lugs
2) Solid state distributor
3) 12V Ignition Coil
4) Ignition Switch

Items 1 thru 4 were done while I attempted to get good spark on my #1 plug with no luck. At no time, through all of these trials have I seen anything less that 11.5V on the + Coil post during cranking.

On Sunday, using bmorgil's suggestion, I was able to start the jeep when I used a jumper from the battery+ to the coil+ post. After turning it off, I removed the jumper and was unable to start or get spark. When I put the jumper back on, the jeep started. After idling for 15 minutes, I turned the jeep off, removed the jumper and it started without the jumper several times. After remounting the ignition switch into the dash, I took it out for a 30 minute drive and when I had it back in the barn, I stopped and restarted it another 5 times with no jumper. I closed the barn, went to the house and had a beer.

On Monday morning, I attempted to start the jeep with no joy. I pulled #1...no spark. Checked my coil voltage during cranking: 11.6V. I applied the jumper from the battery+ to the coil+....no spark.

Since my volt meter isn't showing me where the problem is, my current plan is to disconnect everything but the ignition circuit (e.g. lights, horn, amp meter, fuel gage, fuel pump, alternator) and redo all crimped connections in the ignition circuit on the assumption that I have a faulty connection which shows good voltage but can't carry current reliably. This includes the following cables:
1) Battery + to Amp Meter+ post
2) Amp Meter - post to Ignition Switch BAT post
3) Ignitions Switch IGN + post to Coil
4) Ignition Switch STARTER post to starter solenoid + post

Again, thanks to each of you for your patience and thoughts on this issue. I was reminded on Sunday how much I enjoy driving this old Willy's and look forward to doing it again soon.

Please let me know if any of this recap is unclear.

[51 CJ3]

I agree with your faulty connection theory. It sounds to me like it works when warm but not when cold. Had an airplane do that with the charging system. Fly for a while with everything working then the charging system would just die. 10-15 minutes later it would come back. Impossible to troubleshoot like that. My fix was to rewire the airplane. The problem should be in the circuit or circuits you bypassed to get spark.

[CChris]

If you still have wire directly connected to the battery and no spark:

A. Look at the (-) terminal of the coil with a meter while you are cranking. When the points are open, the (-) terminal should read 12-volts. When the points close, the terminal should read ground. If you always read ground - either the points are not opening and closing or you have an open coil. Since you are back to a real distributor and it ran for a bit - I don't suspect that it just went bad. It was running on the electronic ignition distributor...sorry if I didn't make this clear

B. If you are back to vehicle wiring - not just a direct wire - and you have 12-volts on the (+) terminal while you crank - I suspect a coil issue even more!

This just checks the primary side, there is a way to check the secondary (high voltage) side:

The old redneck way to test a coil was to touch a clip lead on the (-) terminal to ground with the points open. If the top of the coil had 12-volts and that didn't get you spark - the coil was bad.

Bubba would have Junior hold the lead that went to the center of the distributor cap and if Junior jumped and cussed - you probably had a good coil.

With all of the shyte you are seeing - it's about time to swap out the coil for a known good one.I have replaced the coil since I shorted the battery, that doesn't guarantee its good but it is the one that was in the jeep when it was running 2 days ago.

I'm sorry if this wasn't clear in the thread...regrettably it's a long one.

[CChris]

I've re-terminated every connection in the ignition circuit, removed all non ignition related circuits and attempted to start the jeep with and without the jumper and still no spark. I still have 11.6V on the coil + when cranking and have probed the hot lead in the distributor to assure I'm getting voltage there (not while cranking, however).

[bmorgil]

Chris, make sure there is at least 10 volts at the coil while cranking. If there is pull the distributor. Put the points distributor back in. If you want an electronic distributor, buy the Pertronix conversion for your original distributor. There simply is no other explanation for your issue. The Pertronix will be trouble free and you can retain the original look.

[CChris]

Chris, make sure there is at least 10 volts at the coil while cranking. If there is pull the distributor. Put the points distributor back in. If you want an electronic distributor, buy the Pertronix conversion for your original distributor. There simply is no other explanation for your issue. The Pertronix will be trouble free and you can retain the original look.

Thanks, bmorgil. I came to the same conclusion last night. I've been working on the old distributor this morning with the goal of getting it in and giving it a try by tomorrow. It's been a real education for me. Seems like a real simple system which could provide more diagnostic feedback than the electronic "black box". I'll let you know how it goes either way. Again, can't thank you enough for all of your help.

[CChris]

After putting the original (points & condenser) today, I appear to have reliable spark for now. I'll update this after a couple of days to confirm that holds. I'm working on adjusting the timing and getting my wiring buttoned up. Again, thanks to all.

[bmorgil]

Chris, it is important to verify that you have at least near 10 volts while cranking. Any less and two things can happen. The coil will not saturate and generate a spark and the ignition module will not fire. If your ground has resistance or is of insufficient size, or there is resistance in the wiring somewhere the cranking voltage at the coil will be low. The only way to verify this is to draw maximum current (crank the starter) and check the voltage drop at the coil +. It must be near 10 volts minimum or there will be no spark. All electronic distributors have a minimum firing voltage. Points are not sensitive to it but the coil is. The coil is not as sensitive as the electronic module. You could still have the root cause of your problem lurking.

[CChris]

Chris, it is important to verify that you have at least near 10 volts while cranking. Any less and two things can happen. The coil will not saturate and generate a spark and the ignition module will not fire. If your ground has resistance or is of insufficient size, or there is resistance in the wiring somewhere the cranking voltage at the coil will be low. The only way to verify this is to draw maximum current (crank the starter) and check the voltage drop at the coil +. It must be near 10 volts minimum or there will be no spark. All electronic distributors have a minimum firing voltage. Points are not sensitive to it but the coil is. The coil is not as sensitive as the electronic module. You could still have the root cause of your problem lurking.

Interesting...with the points/condenser distributor I'm now getting 10.6V from the + coil post to the - battery post during cranking (with a good white spark). The electronic ignition was always showing 11.6V at the coil (but no spark). By the way, the jeep is running now, I need to wait for my son to come over this weekend to finish tuning. I need his hands, eyes and brain to keep from doing something stupid (e.g. leaving a tool laying near the positive starter terminal).

I'm really at a loss to know why the electronic distributor wasn't sparking with that voltage. Perhaps it's not as easy as poor Chinese quality control? At any rate, I'm investigating the PerTronix Electronic conversion kit you mentioned. I'm a little spooked by OMIX at this point. The OMIX distributor that wouldn't spark was brank new and had not been exposed to "the short"

I'll know this weekend if I'm officially out of the woods, but the signs are good so far. Either way, I'd really like to buy you and the other contributors a beer sometime. If you're ever in Nashville, drinks are on me

Chris