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Topic Summary

Posted by: Rus Curtis
« on: October 05, 2021, 10:50:02 AM »

dielectric is one of my favorite add-ons.  This is good to know.  Glad you got it running!!

Now on to the next issue!
Posted by: GunnersWillys
« on: October 05, 2021, 09:49:48 AM »

Well, it's running!

Rookie mistake.  I never stop making those.  It most definitely was too much dielectric grease. 

I first cleaned the coil wire both ends and the female receptacles on the coil and distributor cap using a stick, paper towels and contact cleaner.  I then had intermittent spark with the test light on the coil wire.  No spark at the plug wires.  Then the same process on the plug wires at the distributor cap, and got intermittent spark on the plug wires.  Used some starting fluid (I hate doing that) to give it a boost, and after a few minutes she fired up and purred.

I was immediately reminded that I need to change the head gasket.  Water vapor out of the tailpipe looks like a fog machine.  I have the gasket, have just been putting it off. 

Thanks everyone.

Richard
Posted by: Rus Curtis
« on: October 04, 2021, 11:29:33 PM »

These ideas are an attempt to move "down stream" from your verifying that the coil is sending spark.  Need to find where that's breaking down now.

Not being an electrician, It's my understanding that while a timing light has clips for the battery for power, the large loop clip (inductive clamp), that goes around the wire senses the pulse through the wire.  So, assuming the light isn't malfunctioning (it could be) the lack of a light from the timing light means the wire isn't transmitting the spark to the plug.  Also inspect that spring tab in the middle of the distributor cap that contacts the rotor.  Hopefully, it's got some good spring and travel to it.

The timing light could also measure the other wires, i.e. blinking light in sync with the spark of that wire but no relation to the timing as that's tied to #1.

Something simple (and really annoying), could be an ill-fitting cable end - either at the distributor cap or the spark plug.  Are the wires copper/metal core or the suppression style?

Posted by: GunnersWillys
« on: October 04, 2021, 09:32:10 PM »

Rus:

Plugs, as you expected, are pretty new.  I have not pulled plugs and checked for spark by holding close to ground.  I'm not seeing any indication of spark on the timing light so I didn't see much point.  I suppose I could.  Can't hurt.

Plug wires are also pretty new.

The coil "plug" wire carries spark to ground in a static test, but doesn't seem to do so when turning over the engine.  It's just me doing the tests.  Maybe I'll enlist some help tomorrow evening and see if the coil wire fires a spark to ground while turning the engine over, same with the plugs.  But a spark should show up on the timing light.

My local FLAPS didn't have a condenser.

One more thought.  I've coated the spark wire ends with dielectric grease.  The intent is to keep out moisture.  Any chance this could inhibit spark?  A quick Google indicates it is possible if you get carried away.  I'll clean it out a bit and see if that helps.
Posted by: Rus Curtis
« on: October 04, 2021, 08:50:32 PM »

Good tests.  I would repeat your test that was performed on the coil to distributor wire (held against engine, observed spark) with each spark plug wire.  Each leg of the spark delivery should give you the same spark show you did manually using a stick.  Have you tried this test while cranking the engine? 

I didn't see any assessment on the spark plugs themselves.  If other components were, "very new," I would guess the spark plugs are too.  How about the wires? 

 
Posted by: GunnersWillys
« on: October 04, 2021, 02:30:19 PM »

Well, back again, same basic issue, no spark.

I haven't started it in 3 - 4 months, busy elsewhere, but when I put it away last time I could not get it to start a few days later.  Decided to get after it this weekend.  Here's where I am after using resources in tech tips.

- Key on, using a 12 volt test lamp grounded to the battery we are hot from switch to + terminal at the coil, strong light. 

- Key on, coil negative terminal where wire leaves for distributor, hot when key on, bright light, no light with key off.

- I also checked the same circuit inside the distributor to see if it was hot at the connection to the condenser.  It was.  I replace and double insulated that wire a while back to insure it was not grounding out as it passed thought the distributor wall.

- Points:  Strong spark, key on, open points with a stick.

- Coil Spark Plug Wire to Distributor:  Pulled distributor end of the wire and held it near the engine, key on, opened points, strong spark.

- Coil: Very new, replaced last round when this happened before.

- Distributor Cap:  Pretty new, looks fine.

- Rotor:  Pretty new, looks fine.

- Timing light to check for spark on plugs while turning over:  Nothing (did get one flash that stopped after the first flash).  Also, I should be able to attach that to the wire from coil to distributor and see spark.  Nothing.

- Condenser:  Pretty new, but I swapped it out for an old one just to see what happened.  Nothing.

I'm not ruling out the condenser as I don't see what else it could be.  I just hate throwing parts at things.  I can pick up a new one if you think it might help.

Thoughts?  Thanks.
Posted by: scoutpilot
« on: December 28, 2020, 05:34:05 AM »

Yes.
Posted by: GunnersWillys
« on: December 27, 2020, 09:32:20 PM »

One more update.  Turns out the cold start issue did not go away.  I'm thinking now it may be a vacuum issue.  Kind of struck me while considering possible causes, so I read up a bit. 

Correct me if I'm off.  Since the engine uses vacuum to draw fuel into the cylinders when starting and running, if there is low vacuum at the carb with a cold start no fuel will make it's way into the engine.  If I hit the carb with some starting fluid it starts right up, then runs fine. 

There is really only one vacuum line, from the distributor advance to the carb.  I checked at the carb, all was tight.  I checked at the vacuum advance, pretty darn loose.  I tightened it up last weekend, and now every day it has started pretty quickly on full choke when dead cold.  This morning was in the 30's.  A little slow, but started about 15 seconds into the crank cycle.

What do you think?  Could this be the issue?
Posted by: GunnersWillys
« on: November 22, 2020, 09:47:56 PM »

Hey, final comment I suppose.  So over the past week, for 3 or 4 days straight I started the 3B using full choke.  Started right up.  I then let it go for three days, didn't want to start.  Full choke, no fire.  Backed off choke and could smell a little fuel, flooded I suppose, no fire.  4 or 5 tries kind of messing with choke location and it fired and ran fine.  This morning, a little hesitant, full choke for 8 or 10 seconds, no fire, backed off a bit and it started.

Bad news is it is finnicky.  Good news is it will start with some effort!  At this point I'm taking what it is giving me.

It mostly just sits in the barn at the moment as I need to bleed the brakes before I take it out on the highway.  They are mushy, a little air in the lines.  I had some brake work done outside and the guy shredded the reservoir cap and I can't get it off.  Good project for next weekend.  After that, steering slop!

Thanks for all the tips!
Posted by: SteveKfl
« on: November 16, 2020, 05:55:54 PM »

You are narrowing it down now.  Every vehicle has its starting quirks it seems.  We have to learn them little by little.  Keep up the progress, and the progress reports too, so we all can learn from it.  Thanks!
Posted by: GunnersWillys
« on: November 16, 2020, 04:58:16 PM »

Update:

The new coil showed up.  For fun I checked the ohms on it, right in the sweet spot.  I pulled the old one, installed the new one, checked the points for spark first.  Great spark!

Jeep still wouldn't fire.  After a few tries I hit it with some starting fluid, which I hate doing, and it stumbled.  Then choked it and it fired right up.  Runs great.

I thought about it a bit and realized I may not have been fully pulling the choke when starting cold.  Just now (a day later) I tried it where I normally start it and it wouldn't fire over.  So I pulled extra hard on the choke lever, and sure enough it moved a bit further and fully closed the butterfly.  After a few seconds it fired right up.  Maybe that is part two of my starting issue.

Thanks for the tips.
Posted by: GunnersWillys
« on: November 11, 2020, 09:26:22 AM »

Got my meter back. Coil tests out pretty far beyond the numbers noted above, so I ordered a new one.  I'll comment back as to whether it fixed things.

Thanks.
Posted by: Rus Curtis
« on: November 09, 2020, 10:48:38 AM »

ouch!

The jumper should connect where the hot wire comes from the switch (closest to the firewall).

https://cj3b.info/Tech/IgnitionSpark.html

This has a diagram showing the wiring.  Added:  Actually has some good tips on troubleshooting - some that we've been discussing already.
Posted by: GunnersWillys
« on: November 09, 2020, 08:29:03 AM »

LOL!  Well, I learned that wasn't a workable test, or at least the way I did it. 

Checked for spark at the points.  Nothing.  Connected a wire to the terminal on the coil closest to the distributor, then touched the other end to the positive terminal on the battery.  Instant Fusible Link!  Apparently I haven't thought this all the way through.

But, checked spark again at the points, great spark!  And jeep fired right up.

I should have my meter back late tomorrow.  I'm waiting on that to test the coil. 

Pretty entertaining.
Posted by: GunnersWillys
« on: November 08, 2020, 07:37:28 PM »

I’m intrigued.  That’s a pretty creative bypass test.  I’ll try it tomorrow.