Engine not starting

[tarry99]

BusaDave,
I got the Jeep back from the "electrician" today. I did a compression check and everything came out around 100 with #8 being a bit lower at 88. Shot a bit of oil in and it went up to 120. Starting going through a check list of electrical items that was posted by someone else but it started raining before I got too far. I did find a bare positive wire and a badly frayed wire coming off the alternator so I replaced those. It wants to start but just doesn't take off. One of my wife's coworkers husband was a mechanic for Jeep. He said he'd love to come look at it and help me out, so we're going to see if a fresh perspective might have an opinion. We all agree that it acts as if it is losing spark after cranking, but I am getting a positive read on the ignition coil with the key in the run position. I wonder aloud if a bad alternator may be the issue. Just grasping for anything at this point. Will keep you posted.

thistle.........Are you kidding me?.......you just got it back from the Electrician and now you find two wires that are bare and badly frayed????? WOW!

 

[BusaDave9]

Sounds like your rings are worn but that's not preventing the engine from running.

The bad alternator wire is not the issue. Nor the alternator itself. If you have enough electricity to turn the starter motor you have more than enough to run the ignition system.

yes it would be nice to get a 2nd set of eyes on this. The main things that would prevent it from running are spark and fuel. I think it must be one of these. It's possible you have these but loose one of them. In other words maybe the spark is intermittent.
Even if you have spark the timing may be so far off it won't run.

Besides spark and fuel the other things that could be wrong would only make it run rough (such as poor compression). I think spark or fuel are the only things that would prohibit this engine from running.

 

[thistle3585]

Tarry99,
Yes. Unfortunately, what used to be a tremendous electrical shop has quickly gone down hill. I thought I'd give him the benefit of the doubt since we've taken work to him for over 20 years but this last time was a fiasco. He also failed to put the spark plugs back in when I picked it up. There is more to the story but enough said.

I think it gets spark during cranking, and tries to start, but as soon as the key goes to run then it loses its spark. Something happens that doesn't allow it to keep firing. We'll reset the timing tomorrow but it was set two weeks ago and it has only sat since then.

 

[BusaDave9]

but as soon as the key goes to run then it loses its spark.

But we still have 12 volts on the + wire on the coil when the key is turned to RUN. Correct?

When the key is set to START there is 12 volts going into the ignition module on the fender. It's a blue wire that then becomes white on the other end of the connector. You may have a bad ignition module. Did you say you replaced it?

 

[thistle3585]

Yes, we have 12 volts on the coil when the key is at run. I did replace the ignition module. I have kept the old one and have put it in from time to time just to double check. I'm thinking I'll pull all the wire from the harness covering and see if there are any bad spots in that blue wire, or anywhere else, and also look at the section between the module and the distributor pigtail.


I'm curious about the fuseable links. How do those work? Should I be looking at those?

 

[tarry99]

Tarry99,
Yes. Unfortunately, what used to be a tremendous electrical shop has quickly gone down hill. I thought I'd give him the benefit of the doubt since we've taken work to him for over 20 years but this last time was a fiasco. He also failed to put the spark plugs back in when I picked it up. There is more to the story but enough said.

I think it gets spark during cranking, and tries to start, but as soon as the key goes to run then it loses its spark. Something happens that doesn't allow it to keep firing. We'll reset the timing tomorrow but it was set two weeks ago and it has only sat since then.

thistle, A while back I mentioned that you should try running a jumper to the coil / Ignition box directly from the Battery thus eliminating the key / Ignition circuit. You would also want to take off whatever circuits are in place to either of those points to totally isolate the Ignition.......A direct ground would also be a good Idea....... Did you ever try that?

 

[thistle3585]

thistle, A while back I mentioned that you should try running a jumper to the coil / Ignition box directly from the Battery thus eliminating the key / Ignition circuit. You would also want to take off whatever circuits are in place to either of those points to totally isolate the Ignition.......A direct ground would also be a good Idea....... Did you ever try that?

Yes, I did that yesterday. No luck.

 

[tarry99]

thistle,


Fuel , Air , Timing & Ignition...........pretty straight forward!

Yes, I did that yesterday. No luck.

thistle,

Something is missing here?

 

[thistle3585]

thistle,

Something is missing here?

You are correct. And three mechanics and an electrician have failed to be able to find it. And a dozen people have stated the same thing that you are saying, but that still doesn't solve the problem. I have a fourth mechanic, that is ASE(?) certified that wants to give it a go so we'll see what he has to say. I'd really like nothing more than to never have to post to this thread again. Time to think outside the box.

 

[tarry99]

You are correct. And three mechanics and an electrician have failed to be able to find it. And a dozen people have stated the same thing that you are saying, but that still doesn't solve the problem. I have a fourth mechanic, that is ASE(?) certified that wants to give it a go so we'll see what he has to say. I'd really like nothing more than to never have to post to this thread again. Time to think outside the box.

thistle,

There is no Mystery here!
Its back to the basic's ............Fuel, Air, Timing and Ignition.
You need to verify cam to Crankshaft timing........
Then Ignition Timing.
If those two Items are correct there is only two things left: 1) a dependable source of power to create a spark and #2 Fuel.

Note: Verifying Cam to Crank timing and Ignition timing is easy.........checking your Ignition box , distributor and it's wiring not so easy.........
If you can verify the Cam, Crank & Ignition Timing and it still will not start I would change out your distributor and Ignition box while still jumping a hot lead directly to your Battery........

Somewhere along the line you folks are missing something!

 

[thistle3585]

thistle,

There is no Mystery here!
Its back to the basic's ............Fuel, Air, Timing and Ignition.
You need to verify cam to Crankshaft timing........
Then Ignition Timing.
If those two Items are correct there is only two things left: 1) a dependable source of power to create a spark and #2 Fuel.

Note: Verifying Cam to Crank timing and Ignition timing is easy.........checking your Ignition box , distributor and it's wiring not so easy.........
If you can verify the Cam, Crank & Ignition Timing and it still will not start I would change out your distributor and Ignition box while still jumping a hot lead directly to your Battery........

Somewhere along the line you folks are missing something!

Again, you are right. I have done all of those things that you have suggested. I have literally replaced every component in the engine compartment except for the alternator. I believe it is getting spark when its cranking then losing it when it goes to the run position. This leads me to believe that it is something in the electrical system specifically the wiring harness, so I will be going through it and testing it.

 

[thistle3585]

Okay, sorry if I got crappy. Here's the deal. We've ruled out air and fuel. We are now narrowing it down within the electrical. We believe that it is a missing or intermittent spark problem that happens when the key goes to the run position. We get spark during cranking. I'm not saying its the ignition switch itself, but that it loses spark once it stops cranking. We have voltage at the coil in the run position. The only thing in the ignition system that has not been replaced is the wiring in the harness, so that is where my focus is now.

 

[thistle3585]

Well, I did something. I was going through the ignition system with a test light and using the attached testing diagram. On another page of that instruction, it suggests adding a ground wire to the ground wire between the module plug and the distributor plug. I hooked it up and it started on the second crank and ran for about 30-40 seconds before dying again and going right back to what it was doing. I must have accidentally hit something when going through the harness, so whatever it is it has to be right in that area.

 

[tarry99]

Okay, sorry if I got crappy. Here's the deal. We've ruled out air and fuel. We are now narrowing it down within the electrical. We believe that it is a missing or intermittent spark problem that happens when the key goes to the run position. We get spark during cranking. I'm not saying its the ignition switch itself, but that it loses spark once it stops cranking. We have voltage at the coil in the run position. The only thing in the ignition system that has not been replaced is the wiring in the harness, so that is where my focus is now.

thistle,

Of Course you have fuel and Air..........that would be the easiest thing to check!
With all do respect.......I have told you to wire around your current harness several times over a period of several days and you have said you have done that but with no result............but now again your focus is back on wiring...............if you would have wired around that circuit correctly in the first place by simply adding a Jumper wire direct from the Battery to your Ignition system you would have already eliminated that Primary wiring circuit and could spend your time elsewhere looking for the real problem.
It is that Simple.............
If you or your people do not know how to wire around that circuit then you should ask.

 

[thistle3585]

Tarry99,
You said run a jumper to the coil. I understood that to mean to run a wire from the positive battery terminal to the positive on the ignition coil. Is that correct? That is what I did without any success. If I misunderstood then please tell me the correct way to do it.

Also, I had already eliminated the "starting circuit" and had moved on to the "running circuit". I have been working through post #3 of this thread. http://www.jeepforum.com/forum/f8/here-we-go-again-not-getting-spark-918041/

 

[tarry99]

Tarry99,
You said run a jumper to the coil. I understood that to mean to run a wire from the positive battery terminal to the positive on the ignition coil. Is that correct? That is what I did without any success. If I misunderstood then please tell me the correct way to do it.

Send a picture...............Do you have an Ignition Box?
On a standard point style system then direct to the coil.....
On an HEI system or one that has a box then to the hot lead at the box.......take off any wires that connects it to your Ignition switch or primary wires.........you want to isolate the system away from existing wiring.
Also needs a good direct ground.............remember if your motor runs it will not shut off until the Jumper is removed......

 

[thistle3585]

Tarry99,
I think you posted while I edited my post. Check my last two posts as I did get it started for 30 seconds.

 

[tarry99]

Tarry99,
I think you posted while I edited my post. Check my last two posts as I did get it started for 30 seconds.

thistle :
This has no bearing on the subject other than it continues to support the need to wire around your existing wiring system with a jumper!..............If the motor starts and runs normally with the Jumper in Place...........now you at least know where the problem is , which would more than likely be in the harness............

 

[thistle3585]

thistle :
This has no bearing on the subject other than it continues to support the need to wire around your existing wiring system with a jumper!..............If the motor starts and runs normally with the Jumper in Place...........now you at least know where the problem is , which would more than likely be in the harness............

Then please tell me how to wire around it. Here is a diagram of my system. What do I disconnect and where do I run the jumper?