no spark to distributor question

[perko]

Hey, I know this has been covered in a million threads, but I had some quick advice to ask. I'm getting 12 volts at the positive terminal of the ignition coil. When I put my inline spark tester between the ignition coil wire and the distributor it shows no spark. The coil is very new, my question is 1. does anyone know the general numbers I should see when i bench test the coil? And 2. Are there any other problems that would result in the coil not sending power to the distributor that I can test for? Thanks.

 

[67Dart273]

Lets start with "what do you have?"

Breaker points ignition?

Mopar OEM/ ECU?

Hei "look alike?"

MSD? Other? Pertronix?

With points, it is going to depend on whether the points are open or closed, and if closed, on whether "things are right" and that the points are actually conducting, that is, not dirty/ corroded, or something else wrong.

So with points closed, or Mopar ECU, with key "on" you should have somewhere between 6--10 volts at the coil.

If points are open, you will have "same as battery"

If an ECU system, if you have "same as battery" either the ECU is not grounded or it is bad

Likewise, with points or closed, key in run, you should have very LOW voltage at coil NEG, perhaps less than 2 volts with ECU and maybe less than that with points.

If the coil NEG is way higher, or same as battery, either the points are bad or corroded, or not closed, or if ECU, then the ECU is bad

I don't remember I believe the above also applies to Pertronix.

It does NOT apply to most GM HEI modules, as they do not draw current with key on

 

[perko]

its a 73 duster, so stock electronic ignition. I just put a test light on it so i don't know if its actually 12 volts but the light was bright. I'll go find my volt meter. My daily driver won't starter either, damn solenoid. I've got to park on hills. Why is everything I own broke?

 

[Sedanman]

Try checking the reluctor gap under the cap. I had one that ran fine on one engine,took it off and it stayed on the shelf for a year or so,went to use it and had the same issue. We checked the gap and it was off,gapped it and it fired.

 

[67Dart273]

Turn the key to "run" and check BOTH sides of the coil. Compare brightness to "full battery."

Coil "plus" should be dimmer than "full battery." Coil NEG should be "quite dim" over "not at all."

IF those are both bright, remove the ECU and check it's grounding. Clean the bolt area, and remount tight. Use start lock washers if you can. The ECU MUST be grounded.

Next, remove the dist. connector, and take up the firewall side of the connector. Tap the BARE terminal of that connector to ground. Each time you do so, one "snap" spark should be generated at the coil.

 

[perko]

Alright, so i've got about 12 volts at both the positive and negative terminal of the ignition coil. I don't have time to check the ECU ground right now, but it looks original so I wouldn't be surprised at all if its bad.

I'm a little confused about this piece of advice

"Next, remove the dist. connector, and take up the firewall side of the connector. Tap the BARE terminal of that connector to ground. Each time you do so, one "snap" spark should be generated at the coil."

does this mean that I take the two pronged connector that goes to the similar connector on the distributor and ground out the exposed metal prong? this will send a snap through the coil which i can see with my tester? This will further prove that the coil is good right?

Any advice on ECUs if i need to get one?

 

[Dartswinger70]

Throw a box on it and see what you got they go bad yeah, you can troubleshoot, but you are going to end up throwing an ignition module at it. Orange box.

 

[67Dart273]

Throw a box on it and see what you got they go bad yeah, you can troubleshoot, but you are going to end up throwing an ignition module at it. Orange box.

So you are paying for this? LOL.

 

[67Dart273]

Alright, so i've got about 12 volts at both the positive and negative terminal of the ignition coil. I don't have time to check the ECU ground right now, but it looks original so I wouldn't be surprised at all if its bad.

I'm a little confused about this piece of advice

"Next, remove the dist. connector, and take up the firewall side of the connector. Tap the BARE terminal of that connector to ground. Each time you do so, one "snap" spark should be generated at the coil."

does this mean that I take the two pronged connector that goes to the similar connector on the distributor and ground out the exposed metal prong? this will send a snap through the coil which i can see with my tester? This will further prove that the coil is good right?

Any advice on ECUs if i need to get one?

Your test indicates the ECU is not conducting. Before you run off half cocked, remove the ECU scrape the mounting and remount, make CERTAIN it is grounded. Another way to tell is to turn the key to "run" as you did earlier. Check coil NEG. If the voltage is high, the box might not be grounded. With one end of the test lamp grounded, stab the probe into the metal housing of the box itself. NOT the head sink........the ECU box. If you get ANY light, the box is NOT grounded.

"Tapping." When you disconnect, you do NOT want the end going to the distributor. You want the end going to the firewall harness. You take that two wire connector, and repeatedly touch the bare end to ground. That is, there's the "booted" side and the exposed "bare" side of the two wires.

Also, "work" all of the connectors.........the distributor, the ballast, and remove the screw in the ECU connector and work it in and out. INSPECT them all with a flashlight for corrosion, and "feel" for tightness

 

[mguner]

Grounding the negative coil terminal momentarily is just emulating points. If coil is good a spark should happen. If it does then the issues lie in the electronic components, their settings or grounds.

 

[Dartswinger70]

So you are paying for this? LOL.

I have been there is all, In my case it was a 1977 Dodge stake body truck, I spent time troubleshooting everything, it checked out good, I even thought the module was good. I took a guess went out and picked up a module, put it on and the thing started up. I guess what I'm saying is, if you don't find anything obvious, try a known good module, see if you can borrow one. Every case is different though. I looked on Summit the box is like 40-45 bucks. That and the module replaces the points, the points are what make the coil fire off spark. In the end, let us know what it was,, and some times when troubleshooting you have to throw a known good part at it, its perfectly acceptable.

 

[67Dart273]

Grounding the negative coil terminal momentarily is just emulating points. If coil is good a spark should happen. If it does then the issues lie in the electronic components, their settings or grounds.

NO. He is not to ground the neg. coil terminal. He is to ground the firewall side of the DISTRIBUTOR connector. This causes the ECU to fire the coil. IE it checks "most" of the ECU AND the coil, as well as power supply wiring to the system, as well as the ECU ground.

Please read the post.

 

[perko]

Ok... So I worked on the duster a little after work today. I tried to ground out the firewall side of the distributor wire (the bare side of the two prong connector) and I got spark showing through my inline spark tester which i have between the middle distributor node and the coil wire. I plugged in back in and it started up just fine. I guess this means that I'm chasing something in the wiring harness? I found three breaks in the insulation of the wirewall side of the connector just after the connector itself and wrapped them in electrical tape. Is electrical tape enough?

Any suggestions on if/how I should investigate this further? Can I buy the ignition side of the wiring harness on its own? I'm about as good with electrical as I am with social media so be gentle.

 

[perko]

Thanks 67dart, that was exceptionally good advice. I never would have thought to ground out the distributor wire.
http://www.forabodiesonly.com/mopar/member.php?u=17025

 

[67Dart273]

This could very well be a poor connection in the distributor connector. If they are not clean and tight, there is VERY VERY little power in that. Only what is generated by the distributor.

 

[perko]

I'll check over the rest of that part of the wiring harness. At least it stranded me in the driveway this time.