Ignition Issue

[Tuck73]

I think I have an ignition switch issue. Turn the key and it starts and runs. After a while it will just shut off. Originally, o thought I had a bad distributor. I replaced the distributor and it starts right up but all then shut off as if you turned the key. If you try to turn the key from the position it is in when it shuts off, it won’t start. If you turn the key to off and then back on, it will start, run for a little while and then shut off. What is the easiest way to test the ignition switch? Any thoughts?

 

[DirtDonk]

The easiest way to test for now would be with a voltmeter. Don’t buy any new parts until you determine when is bad.
Buying new parts often introduces new problems. Just keep that in mind as you’re trying to diagnose any problem.
Not just this one.

First off, what year is your Bronco? Presumably the 73 that’s in your username?
If not, we need to know not only the year, but what else has been done to it. What modifications, what kind of ignition, stuff like that.
Is it an original ignition for a 73? That would mean that you bought a new distributor with points and condenser?
Modern condensers are one of the most common failure points these days. So much so that you’re often better off with a 50 year old condenser that a brand new one made overseas.
Did you adjust the points and set the timing when you installed the new distributor?

Now for the testing… We need some clarification on some of the things you’re talking about, but generally speaking the next time it stops running, don’t touch the key. Just go over and measure voltage at the positive side of the coil.
If there is no power, then it’s either the ignition switch or a wire /connection between it and ignition.

Does the engine ever have trouble cranking with the starter? Or are there times when it won’t even crank? Sounds like the starter is cranking, but the engine won’t catch on fire. Is that correct? Just making sure, because with the term “start“ it could be either.
Or both!

You mentioned that after you replaced the distributor, sometimes it just shuts off when you turn the key.
What exactly does that mean? Which way are you turning the key?
Or are you just moving it?
If you are just jiggling the key and the engine shuts off, I think that’s a pretty good indication that it is in fact the ignition switch.
There would normally be no other possible explanation.

Good luck

 

[B RON CO]

Hi, if you have a tach disconnect it and see what happens. A defective tach could cause the trouble you are having. Good luck

 

[Tuck73]

The easiest way to test for now would be with a voltmeter. Don’t buy any new parts until you determine when is bad.
Buying new parts often introduces new problems. Just keep that in mind as you’re trying to diagnose any problem.
Not just this one.

First off, what year is your Bronco? Presumably the 73 that’s in your username?
If not, we need to know not only the year, but what else has been done to it. What modifications, what kind of ignition, stuff like that.
Is it an original ignition for a 73? That would mean that you bought a new distributor with points and condenser?
Modern condensers are one of the most common failure points these days. So much so that you’re often better off with a 50 year old condenser that a brand new one made overseas.
Did you adjust the points and set the timing when you installed the new distributor?

Now for the testing… We need some clarification on some of the things you’re talking about, but generally speaking the next time it stops running, don’t touch the key. Just go over and measure voltage at the positive side of the coil.
If there is no power, then it’s either the ignition switch or a wire /connection between it and ignition.

Does the engine ever have trouble cranking with the starter? Or are there times when it won’t even crank? Sounds like the starter is cranking, but the engine won’t catch on fire. Is that correct? Just making sure, because with the term “start“ it could be either.
Or both!

You mentioned that after you replaced the distributor, sometimes it just shuts off when you turn the key.
What exactly does that mean? Which way are you turning the key?
Or are you just moving it?
If you are just jiggling the key and the engine shuts off, I think that’s a pretty good indication that it is in fact the ignition switch.
There would normally be no other possible explanation.

Good luck

It’s a 70 with a new Centech wiring harness. The distributor is a new electronic ignition. I removed the old setup with points. When I turn the key to start it will crank and run for a few minutes then shutoff. If I turn the key from the on position, it will not crank. It will just spin but not fire. If I turn the key all the way to off and then turn it to start it will crank and run for a while and then shutoff.

 

[ba123]

That's a weird one but sounds most likely to be a bad connection somewhere...maybe the ignition switch.

Ditto what DD said, don't just restart. Poke around a little. Maybe feel stuff like the ignition switch and see if it feels hot, although maybe some things get hot normally and that's often hard to tell since you wouldn't feel them when not having problems.

But, especially since you just rewired, I would bet it's a bad connection.

Another thing to try to find it, since it's intermittent, is to start it and then jiggle your wiring. maybe start with the back of the ignition switch, then maybe move forward from there.

 

[DirtDonk]

Along the same lines as disconnecting a tachometer, also disconnect the “I“ wire on the starter relay/solenoid.
In the factory harness color it is brown, but in Centech I believe it is white, maybe?
Either way, if it’s connected, disconnect it temporarily and wrap it with tape if it’s an exposed ring terminal.

The most damning evidence of it being switch related, is the fact that it will not restart when you turn it straight from the ON position to start.
Requiring you to turn it back to OFF first, then to start, indicates to me a bad switch.
However, the ignition switch isn’t the only switch involved here. Because potentially the starter relay is directly connected to the ignition coil too, and it could also be defective.

And the bad ignition condensers I mentioned before are second only to the sheer number of defective starter relays people buy these days.
So, if your new harness is using a wire connected to this starter relay’s I post, definitely disconnect it.

And just for our information, what kind of electronic distributor did you buy?

 

[Tuck73]

Along the same lines as disconnecting a tachometer, also disconnect the “I“ wire on the starter relay/solenoid.
In the factory harness color it is brown, but in Centech I believe it is white, maybe?
Either way, if it’s connected, disconnect it temporarily and wrap it with tape if it’s an exposed ring terminal.

The most damning evidence of it being switch related, is the fact that it will not restart when you turn it straight from the ON position to start.
Requiring you to turn it back to OFF first, then to start, indicates to me a bad switch.
However, the ignition switch isn’t the only switch involved here. Because potentially the starter relay is directly connected to the ignition coil too, and it could also be defective.

And the bad ignition condensers I mentioned before are second only to the sheer number of defective starter relays people buy these days.
So, if your new harness is using a wire connected to this starter relay’s I post, definitely disconnect it.

And just for our information, what kind of electronic distributor did you buy?

I will try all of this tonight and report back.

As for the distributor it’s the Jeg’s Ready to Run (RTR). They claim it should the same as MSD with their on brand on it.

Also, once I disconnect from the solenoid, what do I do? Just disconnect and see if it runs?

 

[DirtDonk]

Yes. Basically you're only eliminating the one thing that the ignition and starter relay have in common. That's the "I" wire that is there only to provide extra voltage and current to the ignition during the starting process.
With your new distributor it should not be as necessary, and even if it was still points and condensers, it would still run without this connection.

The other small wire on the starter relay is the one that cranks the starter. The old wire was Red w/blue and the new one is Violet/Purple.
This wire is on the "S" post and does not need to be disconnected.

So to be clear, all wires remain connected to the starter relay, other than the one wire connected to the "I" post.
Whether this is one of the Blue wires, or the White wire, or some other color, I just can't remember. But it should say something along the lines of "Ign" printed along it's length. So you can tell us what you have and what you don't.
Maybe even post up a picture of the starter relay, ignition coil and distributor area(s) and anything else that might pertain.

Also, which ignition switch are you utilizing? Is it the factory style switch, or the "tractor" style that used to come with the Centech basic harness?
And if the standard Bronco switch, is it a brand new one, or the old one?

Paul

 

[Tuck73]

Yes. Basically you're only eliminating the one thing that the ignition and starter relay have in common. That's the "I" wire that is there only to provide extra voltage and current to the ignition during the starting process.
With your new distributor it should not be as necessary, and even if it was still points and condensers, it would still run without this connection.

The other small wire on the starter relay is the one that cranks the starter. The old wire was Red w/blue and the new one is Violet/Purple.
This wire is on the "S" post and does not need to be disconnected.

So to be clear, all wires remain connected to the starter relay, other than the one wire connected to the "I" post.
Whether this is one of the Blue wires, or the White wire, or some other color, I just can't remember. But it should say something along the lines of "Ign" printed along it's length. So you can tell us what you have and what you don't.
Maybe even post up a picture of the starter relay, ignition coil and distributor area(s) and anything else that might pertain.

Also, which ignition switch are you utilizing? Is it the factory style switch, or the "tractor" style that used to come with the Centech basic harness?
And if the standard Bronco switch, is it a brand new one, or the old one?

Paul

Unhooked purple wire to solenoid. (Is red in pic because original wire wasn’t long enough) once disconnected it would not turnover. Connected it back and started right up. Ran 5 minutes and shutoff. Didn’t touch key or anything and tested voltage to coil. 12 bolts were running to coil with key in run position.

 

[Tuck73]

 

[Tuck73]

 

[Tuck73]

Yes. Basically you're only eliminating the one thing that the ignition and starter relay have in common. That's the "I" wire that is there only to provide extra voltage and current to the ignition during the starting process.
With your new distributor it should not be as necessary, and even if it was still points and condensers, it would still run without this connection.

The other small wire on the starter relay is the one that cranks the starter. The old wire was Red w/blue and the new one is Violet/Purple.
This wire is on the "S" post and does not need to be disconnected.

So to be clear, all wires remain connected to the starter relay, other than the one wire connected to the "I" post.
Whether this is one of the Blue wires, or the White wire, or some other color, I just can't remember. But it should say something along the lines of "Ign" printed along it's length. So you can tell us what you have and what you don't.
Maybe even post up a picture of the starter relay, ignition coil and distributor area(s) and anything else that might pertain.

Also, which ignition switch are you utilizing? Is it the factory style switch, or the "tractor" style that used to come with the Centech basic harness?
And if the standard Bronco switch, is it a brand new one, or the old one?

Paul

I forgot to mention I’m using a new switch from either Wild Horses or Tom’s that is a Bronco switch not tractor. I have less than 1,000 miles on build.

 

[DirtDonk]

Unhooked purple wire to solenoid. (Is red in pic because original wire wasn’t long enough) once disconnected it would not turnover.

Naturally. Just what would be expected.
Purple wire is what energizes the starter.
Normally has nothing to do with the ignition system, but in this case I see you are using a PMGR/mini starter. Does the lack of a picture mean that you no longer have a Ford starter relay on the fender?

To make sure we’re all on the same page here, is your ignition switch connected directly to the starter solenoid on the starter?
No more starter relay on the fender?
Positive battery cable runs straight down to the starter?

And even though this is unrelated, or should be, is it just the angle of the picture, or is your starter cable awful close to the header tube?
I don’t see any signs of melting or burning, but it sure looks close!

Didn’t touch key or anything and tested voltage to coil. 12 bolts were running to coil with key in run position.

Well, that’s both good and bad.
Good because it supposed to be there, bad because it would’ve been nice to find something obvious.
I wonder if the coil is overheating?
It shouldn’t, because that type of coil is usually made for 12 V. But you never know.
Next time you fire it up, have a jug of cold water handy and when it dies, cool the coil down with the water.
Or, when it gets close to the five minute mark, just start cooling the coil down anyway to see if it idles longer.

What are the three wires going to the coil?
Specifically the orange wire?

 

[Tuck73]

Naturally. Just what would be expected.
Purple wire is what energizes the starter.
Normally has nothing to do with the ignition system, but in this case I see you are using a PMGR/mini starter. Does the lack of a picture mean that you no longer have a Ford starter relay on the fender?

To make sure we’re all on the same page here, is your ignition switch connected directly to the starter solenoid on the starter?
No more starter relay on the fender?
Positive battery cable runs straight down to the starter?

And even though this is unrelated, or should be, is it just the angle of the picture, or is your starter cable awful close to the header tube?
I don’t see any signs of melting or burning, but it sure looks close!


Well, that’s both good and bad.
Good because it supposed to be there, bad because it would’ve been nice to find something obvious.
I wonder if the coil is overheating?
It shouldn’t, because that type of coil is usually made for 12 V. But you never know.
Next time you fire it up, have a jug of cold water handy and when it dies, cool the coil down with the water.
Or, when it gets close to the five minute mark, just start cooling the coil down anyway to see if it idles longer.

What are the three wires going to the coil?
Specifically the orange wire?

12 volts runs straight to starter, no relay. As for wires to starter, the picture makes it look closer than it is. They are clamped to the frame until you t turns to the starter. I will have to check on orange wire. Comes from firewall.

 

[Tuck73]

12 volts runs straight to starter, no relay. As for wires to starter, the picture makes it look closer than it is. They are clamped to the frame until you t turns to the starter. I will have to check on orange wire. Comes from firewall.

Orange wire has FLD stamped on it and cones from the firewall. I believe it’s the hot coming from the ignition strip.

 

[B RON CO]

Hi, the orange wire from the firewall looks out of place, especially with the crimp on connector. I would unhook it and see if the engine runs. Generally, a coil needs one wire from the ignition switch, and one wire to the distributor. Any extra wires are usually for a tach, or a Pertronix ignition, or something like that. A long shot would be that perhaps the coil base needs a better ground, or a better heat sink. Good luck

 

[DirtDonk]

The "field" wire is not normally supposed to be associated with the ignition system at all.
Perhaps it was repurposed by the installer?

It's normal function is to connect the external regulator directly to the alternator. There is "normally" NEVER another component that this is connected to.
It's only for external regulators, and only goes between the regulator and alternator.

Definitely disconnect it and see if it's got power with the key. If it does, then it has definitely been repurposed.
Unless Centech has changed something?

Verify what the other two wires do too of course. Which you may already know because you replaced the distributor just a few days ago.

Paul

 

[Tuck73]

The "field" wire is not normally supposed to be associated with the ignition system at all.
Perhaps it was repurposed by the installer?

It's normal function is to connect the external regulator directly to the alternator. There is "normally" NEVER another component that this is connected to.
It's only for external regulators, and only goes between the regulator and alternator.

Definitely disconnect it and see if it's got power with the key. If it does, then it has definitely been repurposed.
Unless Centech has changed something?

Verify what the other two wires do too of course. Which you may already know because you replaced the distributor just a few days ago.

Paul

That larger orange wire with blue ring connector is the hot wire from the ignition to the coil. The red wire is the positive from the coil to the distributor. The orange wire from the coil to the distributor is the negative and there is a black wire that is a ground.

 

[DirtDonk]

OK, sounds good. I guess the field wire got repurposed.

Have you checked ignition timing with the timing light since you put the new distributor in?

And just to be certain what you were saying previously, when the engine is running, and then stalls, you have power to the ignition coil still?
Or did that previous test begin with just turning the key to run and checking for voltage?
If so, have you run it until it died and then checked for voltage again?

Last question for now. Is this carbureted or fuel injected? I realize that should have nothing to do with the starter not cranking, but it is just more good information. Things to know…

 

[DirtDonk]

Speaking of things, to know… Connecting your ignition switch directly to the new starter is not the preferred method.
There are two reasons for this, one of which you don’t seem to be suffering from.

Most people suffer from starter run-on after they release the key from start to run and find that the starter is still cranking for a few seconds.

The other problem, possibly pertinent here, is that directly to the starter takes more current than the original switch was expecting when designed.
Yes, it should be able to handle it, but so far a huge percentage of people who are using the modern starters wired this way end up wearing out their ignition switches extremely quickly.
Perhaps this is what’s happening to you?

The only thing I’ve ever come up with, as an explanation, is either bad luck, or the ignition switch is just can’t handle the slight extra current of a starter solenoid.
After all, the original design did not include a starter “solenoid“ specifically. The part on the fender that we often referred to as a solenoid, is actually a relay that, whose only duty is to close the electrical contacts.
The actual current used by the ignition switch is very minor. Whereas the larger coil windings and heavier duty nature of the work that a solenoid does, requires more current.
Of course, this is just guessing on my part, as I have never seen a specific rating of just how many amps it takes to close a Ford relay, versus closing an actual starter solenoid.