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No spark issue... car died on the way home from getting gas


erikquick

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Good morning friends,

 

I've got a little learning to do...

I took the '52 out to get gas the other night. She ran fine after warming up. I filled up the tank and headed home. No drama. But then, she just died on me at a light.

Turns out I was no longer getting spark to the coil (so I think).

 

I'm a little confused about the way this ignition coil is wired up. The car has been converted to 12 volts, and that is all done nicely and neat under the dash.

I put my meter to both the ballast resistor and the ignition coil to better understand where I might be losing juice.

Turns out, there is power going to the ballast resistor, but it's a constant 12V - doesn't seem right. Shouldn't that be on ignition only?

Anyway, then I metered the two posts on the ignition coil. Both look to be "positive ground" at rest with ignition off and the wires connected to the ballast resistor. 

Doesn't make any sense to me. 

 

Before I go crazy and start replacing parts (not that I mind new parts now that I am the new owner), I just need to understand how to diagnose my no-spark issue on a system like this. 

A few troubleshooting ideas are welcome.

Pics below.

Thanks!

 

 

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Is it still a points distributor, or has it been converted to electronic ignition?

If it has points, with the points open you will read 12 volts at every point throughout the circuit because there is no current flow. Once the points close you should see 12 volts input to the ballast resister, 6ish volts out of the resistor and at the + of the coil, and 0 volts at the - terminal of the coil. If it's an electronic ignition then more information on which system is required.

It appears to have 2 or 3 wires on the + terminal of the coil. What else is connected into the ignition system? Maybe that is interfering with your readings.

Also curious that there is, what appears to be, a flasher tied in to the ballast resistor. What is that for?

 

Edit: Another important question... Where do you have your other test lead attached? If it is connected at a power source then your negative reading means that the red probe is on a grounded connection.

 

Edited by Merle Coggins
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Have a look at the little jumper wire inside the distributor.  Very likely it is grounding out on the case.

 

If the car ran satisfactorily up to the time it quit , there is no major issue with how it is wired.   

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2 hours ago, dpollo said:

Have a look at the little jumper wire inside the distributor.  Very likely it is grounding out on the case.

 

If the car ran satisfactorily up to the time it quit , there is no major issue with how it is wired.   

Boy, I can relate to that small pigtail wire shorting out. I had that happen one time at night when it was 6 degrees outside. I was just a young kid and had no idea what to look for. An old time mechanic straightened me out when he told me to check it. When it shorts out, it sure interrupts you trip.

John R

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I had the same problem only it was not the wire inside the distributor- it was the condensor. A lot of parts are made overseas these days  and just don’t last they way they should. I swapped mine (which was hours new when it failed) with another new one, problem solved. I later searched at swap meets and found some older NOS pieces to keep as back up. Problem with these is in a 52 distributor (and maybe other years as well), you have to disturb/readjust the point gap when removing and installing the condensor. Pain in the behind.

 

Ultimately what I am going with is a chrysler electronic ignition distributor and GM HEI ignition and ford coil. Lot of zap for the money. If you are interested the conversion is well documented on this site. You need a slant six distributor and a flat head donor distributor to make the change over, you then have the choice of mopar ignition box or or brand x types. I chose brand x for higher energy spark.

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17 hours ago, Merle Coggins said:

Is it still a points distributor, or has it been converted to electronic ignition?

If it has points, with the points open you will read 12 volts at every point throughout the circuit because there is no current flow. Once the points close you should see 12 volts input to the ballast resister, 6ish volts out of the resistor and at the + of the coil, and 0 volts at the - terminal of the coil. If it's an electronic ignition then more information on which system is required.

It appears to have 2 or 3 wires on the + terminal of the coil. What else is connected into the ignition system? Maybe that is interfering with your readings.

Also curious that there is, what appears to be, a flasher tied in to the ballast resistor. What is that for?

 

Edit: Another important question... Where do you have your other test lead attached? If it is connected at a power source then your negative reading means that the red probe is on a grounded connection.

 

Thanks, Merle, and all.

So, more info...

It's still a points distributor. I'll see what else is connected to those other 2 wires on the + coil, but I know one goes to the case of the distributor.

My other test lead is on the batter y positive. When my other (neg) lead was on negative terminal, I had no voltage readings to the coil. And I have no idea if my coil is a 12V or 6V coil. And yeah, no idea why the flasher relay is wired in parallel to the wire at the input side of the ballast resistor. The original Plymouth service manual says nothing about that, and I would REALLY like to have this car wired the way it's supposed to be - as original as humanly possible. Whoever had the car last got it running (and it ran well before it died), but definitely seems to have been a bit of a hack electrical front. Irks me to no end. 

Edited by erikquick
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4 hours ago, erikquick said:

Thanks, Merle, and all.

So, more info...

...My other test lead is on the batter y positive. When my other (neg) lead was on negative terminal, I had no voltage readings to the coil...

 

So, if your black test lead was on the positive post of the battery then you have a grounded out ignition ciucuit. Based on that info, and the two pictures of meter and coil test, both terminals are grounded. Trace out those wires on the + terminal of the coil. Or disconnect them and test each one individually to find which one is grounded out.

If one of the wires on the + side is going to the distributor case, that would likely be going to your points. The points are the ground for the coil and should be on the - side, assuming negative ground system. If it has an electronic ignition module in there then that would change things considerably. Where does the wire on the - side go?

 

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Edited by Merle Coggins
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Looks like it's powering that flasher from the ignition +. That shouldn't be a problem, particularly since it had been running okay. Make sure it's actually not firing at the spark plugs. With points there should be a hot wire to the coil from the ballast resistor on your car, and the other side of the coil should attach to the distributor. Ballast resistors don't go bad very often. You can remove the leads from it and check it for resistance. If you suspect it of being bad jumper across it. Check for voltage at the points. I use a test light instead of a meter with points ignitions. With the distributor cap off you can just open and close the points with a screwdriver and see if there's spark at the points. If you have spark there but the plugs still don't fire then you can start looking at the rest of the ignition. I'd be surprised if it's something other than a bad condensor, bad coil or coil wire, or the wire in the distributor as already mentioned.

 

Edit to add: Make sure the points are actually opening and closing. About 45 years ago I had to rescue my younger brother for just such an occurrence. Rubbing block had worn down. 

 

This link is for a Type 1 VW but the ignition works the same.

 

http://www.shoptalkforums.com/viewtopic.php?p=972722

Edited by MackTheFinger
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Update to all.

I will need to look into the distributor (yes, it's points) to see if it's grounding out. However, I'm still confused about how this ignition coil is wired up.

To be honest, I don't know anymore which side is SUPPOSED TO have the 3 wires to it and which side is SUPPOSED TO have ground.

 

I have a positive ground system... I put my meter lead on the main ground wire to the engine and put my other lead on the battery terminals. I got 12V when one lead was on the negative battery post and the other on the chassis ground.

 

With that being said (that I have a positive ground system), am I supposed to be hooking up the 3 leads to the (-) on the coil? Or the (+)?

For more context, there are 3 wires together on one post of the coil. They go to come from:

1. a +12v source (it's a constant 12v although I think it should be ignition)

2. a wire that goes to the body of the distributor

3. a wire that goes to the carburetors (one wire splits to two)

 

The other side of the coil has one wire. It goes to ground, but is on a momentary switch that is under my dashboard. When you push in the switch, it interrupts the ground. (IMG6108 is the switch, IMG6019 is the ground point for the momentary switch, IMG6110 is the other side of the momentary switch that goes to the coil)

 

So confused!

Thoughts?

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Yes, I'm confused now too. You have a 12 volt system that is positive ground? That's quite strange. I don't know why someone would go to the work of upgrading to 12 volts system and not switch to the more common negative ground. I'd be switching that if it were mine.

 

So, you are saying the the wire from the - terminal of the coil goes to the push-button switch and then to what appears to be your starter solenoid? Again quite strange. Are you sure it's a ground terminal on the solenoid? Have you used that button for anything since owning the car?

As for the + terminal, you say one wire is always 12v hot, and one goes down to the distributor terminal? That wouldn't make any sense either. You'd be sending voltage directly to the points. Whenever the points close it would be a direct short on the 12 v power source. And the wires going to the carburetors appear to be powering up electric choke coils. Those would need power when the key is on. Based on this information I'm surprised that it even ran in the first place.

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1 hour ago, Merle Coggins said:

Yes, I'm confused now too. You have a 12 volt system that is positive ground? That's quite strange. I don't know why someone would go to the work of upgrading to 12 volts system and not switch to the more common negative ground. I'd be switching that if it were mine.

 

Yeah, happy to tackle that.

 

1 hour ago, Merle Coggins said:

 

So, you are saying the the wire from the - terminal of the coil goes to the push-button switch and then to what appears to be your starter solenoid?

Yes, no idea why and I’ve never touched that button.

 

1 hour ago, Merle Coggins said:

 

Again quite strange. Are you sure it's a ground terminal on the solenoid? Have you used that button for anything since owning the car?

As for the + terminal, you say one wire is always 12v hot, and one goes down to the distributor terminal?

 

Yes, it’s crazy. The wire coming from behind the ignition switch is hot (12v constant) and it was going right to the ballast resistor. That is the same wire that has the flasher relay tagged to it. I know it should be ignition; I can throw it on a relay so that it’s only on on ignition. As an aside, I have already fixed a “no-no” that I saw when i first got the car... the electric fuel pump was on a big a** paddle switch, giving it 12v constant regardless of ignition position. I already fixed that and put the system on a relay so that the pump is only on with ignition.

 

1 hour ago, Merle Coggins said:

 

 

That wouldn't make any sense either. You'd be sending voltage directly to the points. Whenever the points close it would be a direct short on the 12 v power source. And the wires going to the carburetors appear to be powering up electric choke coils. Those would need power when the key is on. Based on this information I'm surprised that it even ran in the first place.

 

Weird, but it did... I’ve got a basic MECP certification and I’ve been around car electronics for 20+ years. But all modern cars, and never came across something this confusing. 

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OK, back up a bit here...

Wire off the ignition switch goes to the ballast resistor, same terminal as the flasher feed. Yes?

The wire at the other end of the ballast resistor is the one that goes to the + terminal of the coil? And this one has 12 volts all the time, or just with key on?

Wire going to the distributor/points should be on the opposite terminal of the power source regardless. This is wrong if it is also on the + terminal. Move it to the - terminal.

Now that I know you have a pos. ground system the negative 12v at the coil terminals makes more sense. With no completion to ground through the points you will read 12 volts, even through it is going through the ballast resistor and the coil primary circuit. This is because there is no current flow. It is only potential voltage.

 

Remove the wire going to the distributor and use your meter in the Ohms setting to check for continuity to ground. While testing this remove the distributor cap and inspect the points. When the points are closed you should have continuity to ground on the distributor wire/terminal. When the points are open there will be no continuity. If no continuity with the points closed you will need to do some more investigation within the distributor. Possibly a bad internal wire or burned points that are not truly making contact.

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Piggybacking on Merle’s Answer and in response to something that’s come up twice. You mention 12 volts to the ballast regardless of ignition position. So is that to mean you have constant 12 volts? If so, you’ve likely burnt up your points or coil. Although if so, I also don’t know how you could turn off the car! Can you clarify the 12 volt constant issue?

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Hey all,

 

Made more progress. Some good news. It IS a 12-volt negative ground system.

 

- the flasher relay had shorted out; I pulled it and things started looking "normal" again.

- now I have 12V ignition coming in to the ballast resistor. 

- so, going to the + post of the coil is the (a) out from the ballast resistor, (b) to the electric choke, and (c) to the distributor housing --- which I still don't understand.

- the - post of the coil was going to the starter solenoid, through that momentary button under the dash, which all seemed kinda dumb. So I moved it directly to chassis and took that switch out of the loop. so now, - on the coil goes directly to chassis ground.

 

I pulled the distributor cap off and looked at the points. Was going to meter for continuity, but it started to rain. So, she's covered back up and I'll attack this again soon. 

 

More to come - thanks all!

Erik

 

 

 

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It's hard to imagine the flasher causing your problem unless it's shoring everything to ground. You'd think there's be a fuse somewhere in this system but it's easy enough to disconnect the flasher to rule it out.

 

To my recollection, the function of the ballast resistor is to allow full voltage to the coil when the engine is starting, then dropping the voltage to keep from burning up the coil, condenser, points, etc. It should only see voltage when the ignition is on. 

 

As for your original problem, the car was running and suddenly it isn't. From that you would assume a component failure, not a fault in the way it was initially wired up. Look at that VW ignition wiring diagram I linked to. That's really all there is to it. 

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1 hour ago, MackTheFinger said:

 

To my recollection, the function of the ballast resistor is to allow full voltage to the coil when the engine is starting, then dropping the voltage to keep from burning up the coil, condenser, points, etc. It should only see voltage when the ignition is on. 

 

Very true.  The ballast resistor in the photo has only 2 terminals so the points always see reduced voltage.   That's why I think the pushbutton is a bypass.  There are '4-terminal' ballast resistors (beginning around 1972 for Mopar with electronic ignition) that allowed full voltage during cranking.

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no external resistor allowed for full voltage when cranking....it is the by-passing of this resistor from the start contact of the ignition switch that applied full power to the coil, the run circuit is the one that drops the voltage on the coil so not to overheat it when in operation.   The OP needs to get familiar of how an basic points ignition system works and if he does not have an owners manual at hand, there are so many good white papers on the internet that simplify the operation and offer excellent simple tests for each component.  I suggest a sit down and read session.

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