1982 CJ8 six cylinder spark problem

Some stores, NAPA, maybe others will also test the module for you. BUT the test is not always conclusive. I had a bad module that tested fine on the machine but had just left me stranded. Your problem sounds alot like what was happening when mine went bad. Would be driving down the road then the motor would just start missing. One thing I was told was to watch your tach, if you have one, if it is dropping to zero, while the motor is missing then it is you module.

Have you checked the voltage at the coil? If your `82 is the same as my `79, the coil gets full battery voltage while cranking from a terminal on the starter relay, then drops to a lower voltage (via a resistive link spliced into the harness) while running. If there's a corroded splice or terminal in the "run" circuit someplace, you'll get easy starts (full voltage) but crappy running (low or intermittant voltage).

Just a thought.

An update -- Still no luck.

Have now replaced the ignition module AND the distributor (with a rebuilt unit). So this goes along with new plugs, wires (twice), distributor cap and rotor (twice).

I have read other recent suggestions and will be following up on those too.

Please give any more advice you can, because I've now become very frustrated ......

Mike

Michael Pomeroy

Not enough gas getting to the cylinders at idle is still my guess.

I also changed everything including the freaking distributor.

Those damn inductive timing lights are crap for diagnosing a 'miss', believe me. If you do a google search on me you will find the post where I got suckered by the timing light last summer sometime.

When was the last time you changed the gas filter?

Is the gas filter in right side up? That can really mess you up. The center outlet goes to the carb and the top outlet goes to the return line.

If the return line isn't at the top and if the filter is even slightly plugged, the gas will take the clear bypass line back to the gas tank and it will starve the carb for gas. The bypass line isn't filtered so you can blow through it even when the center outlet is blocked solid.

Oh, how about the idle mix screws on the carb? If too lean, the timing light can give the same crap for readings. If all else fails, maybe set the carb up richer to see if that allows you to set the timing. It will run richer no problem.

The engine will run rough and have a burble or miss in it if the carb is set too lean. Did the same person set the new carb mix up as the old carb? Maybe they don't know the proper way to set the mix?

You also could just have a crappy timing light.

Could your intake manifold be loose? That will lean the crap out of it at idle and is a pretty common thing to happen. Even more common is for the carb to come loose after replacement. This also will lean her out big time.

Good luck....

Mike

snipped-for-privacy@yahoo.com wrote:

Took your advice and checked some voltages.

Battery (all measured with a multimeter across the battery terminals): 1: Prior to starting = 13.2 2: While starter engaged = 11 3: While running at a very fast idle = 14.5-14.6

Voltage to coil (measured with a multimeter from the negative battery terminal to the red wire on top of the coil itself): 1: With engine off but key on = 7.6 2: With engine running at a fast (though ragged missing) idle = 10.9-

And, note, this 10.9-11.2 was bouncing around constantly, not staying steady at all.

Make any sense? Provide any clues??

Mike

Michael Pomeroy

A cheap o'scope works reasonably well if it is due to a plug wire, defective plug, or poorly grounded plug. Any difference between the plug waveforms is usually a good place to start.

I wonder if there is a small undetected vacuum leak making it lotsa fun here.

Mike

Tried all the suggestions here except the fuel filter.

Took the ignition module back off, scrapped some bare metal from the fender where it mounts and connects, and made sure it was tightened back down well. No help.

Took some booster cables and tried all of the areas you suggested. Great suggestion I'd have never thought of, and to keep in the mind for the future.

But no improvement noted at all.

And this engine is missing bad, even when revved up. It is not driveable. But the problem is not just at idle -- it is at ALL engine speeds.. From a fast idle, which is what is required to keep it running, all the way through a fast RPM.

And this may not be the only problem I have, but with either of the two timing lights I have you can see the erratic flashing at ALL engine RPMs. (It seems more erratic at slower RPM, but that may be my imagination or misinterpretation.

(And, of course, I had to check out the timing lights again to make certain what I was seeing was real and not an artifact of the light itself. So I again put one of them on my 91 Cherokee and it worked just fine.)

Mike

Michael Pomeroy

That is perfect.

You have no power to the coil issues.

The power comes through a ballast wire that acts like a voltage regulator sort of. It lowers the voltage.

The pulsing is because the negative on the coil pulses from the distributor pickup to send the spark to one cylinder at a time by shutting off the coil.

Mike

snipped-for-privacy@yahoo.com wrote:

Mike

Checked the fuel filter. (It is only 6 months old, probably has 250 miles on the motor since then.)

It WAS upside down based upon your description below.

Fixed; right-side-up now.

But no difference in the problem noted.

Mike

Michael Pomeroy

All speeds sure does change things.....

Do you have a computer in that 82? Or are you lucky and it was just before them?

For the cost, changing the fuel filter can't hurt....

I would also try unplugging the plug at the side of the alternator as well to see what happens. Your alternator sounds ok, but a short in there can pull the coil signal down. The small brown wire to the alternator excite tags the coil power. Just a thought.

I also would pull the dipstick and have a smell of the oil. If the fuel pump is failing it will pump some gas into the oil and the smell will be there.

Do you have a tachometer? If so, factory or aftermarket? I have seen aftermarket tachs go bad and cause a spark miss.

Mike

snipped-for-privacy@yahoo.com wrote:

^^^^^^^^^^^^^^^^^^^^^^^^^^^^

I wonder, the load of the coil shouldn't pull the voltage down enough to make the meter bounce badly, and just because a meter sees voltage it doesn't mean that there's enough current there to be useful.

Try this: Pull the connector off the coil (carefully, because the clips are easy to break when they get old), it is a half-moon shaped affair that mates with two posts on the coil. The (+) wire is fed constant

Then: Rig a jumper to the red (coil +) connector at the coil, protect the free end somehow so it doesn't make contact with anything and smoke your wiring harness. Start the engine and touch your jumper to the + battery terminal -- what you're doing here is bypassing all the harness wiring between the battery and the coil. Don't leave it on too long because you're over-volting the coil. If the engine straightens up and runs smooth, you've demonstrated that there's a problem in the system that feeds the coil. That narrows it down to:

- The connection at the coil.

- The splice where the wire for the "I" terminal comes in.

- The splice where the resistive link (a stiff wire a couple of feet long with a loose, rubbery insulator, probably a different color red from everything else) comes in. Probably at the "I" terminal.

- The splice where the resistive link goes back into the harness.

- The bulkhead feed-through at the fire wall.

- The connector at the bottom of the steering column.

- The ignition switch.

- Any non-factory splices POs made in that line under the hood looking for B+ sources.

Disclaimer: I'm not a mechanic. I'm only telling you what I would try. Doing any of this is completely at your own risk.

Mike

Girl friend's hair dryer works very nicely for checking heat issues of electronics. Less waiting, easier to direct the hot air.

Fixed-at least for the past two weeks. Have driven it daily.

What a saga I went through; still not sure what was wrong or what fixed it exactly?! To do a summary recap of it all in the order it finally happened as best I remember it (and I'm probably forgetting something).

*** Nothing seemed to have any effect motor would barely run ***

So what happened; I don't know, and I'm keeping my fingers crossed.

Thanks to all of you for your suggestions ......

Mike

Michael Pomeroy

The coil power wires can get brittle and start to pull apart. Pushing the clip back on might have shoved enough strands of copper back together to allow a decent spark.

Just a wild assed guess, but it happened to me out in the bush on New Years. It started losing power then up and quit on me.

I went looking around then noticed a crack in the insulation going to the coil negative connection. Sure enough only one copper strand holding that let go as soon as I touched it.

Mike

snipped-for-privacy@yahoo.com wrote:

The coil wires on the primary side or the high-voltage side?

Mike,

That's what logic would seem to say, that there is some problem with this clip/these connections. But try as hard as I can, I couldn't observe anything bad at all; nor could I make it fail.

I'll keep watching and messing and see what happens and let you know if I come up with anything. (If it does turn out to be that, I replaced a lot of parts unnecessarily. Of course, now I've got some good old spare stuff.)

And thanks to you guys I've learned some things.

I've driven the Scrambler more the last two weeks, probably, than I did all of last year. Plan to keep driving it as my daily driver for a while so we shall see.

Thanks ..... Mike

Michael Pomeroy