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2G to 4G help!!

jimmyk

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I'm helping a friend convert his 302 from a mustang front dress to the explorer. We have changed everything over but can't get it to start (ran fine before). I wired the alternator the same as my 4G but can't get it to fire. He does have an MSD 6AL box whereas I do not, but I don't believe it should matter regarding this issue. I have fire at the coil but nothing at the plug wire (good way to wake you up!!). I know there was an extra plug on the 2G alternator, although I'm not sure what it was for (two wires going into one, looks like a ground wire ).

The plug on the 4 G alternator is wired the same as mine (yellow back to Alt post, white/black not used, and green to "I" post on the solenoid along with the Gn/Red from the wiring harness. Any thoughts on what it could be is appreciated!!
 

Broncobowsher

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Unplug the alternator and check for power to the turn on wire. Forget the color, but function wise the one that goes to ignition. Not knowing how the mustang is wired, you may have popped a fuse or something.

FYI, the engine should run just fine without the alternator hooked up at all. For as long as the battery has enough charge anyway.
 

DirtDonk

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You have an incorrect interconnection.
There’s no way a normally wired alternator affects the ignition and there’s no way that a wire from the alternator should be connected to the I wire of the starter relay.
The I wire is directly connected to the ignition coil and should not have anything to do with your alternator.

So do as was suggested and disconnect the alternator, or just disconnect the wires from the I terminal of the starter relay.

What is at the other end of the Green wire? There should only be a Green with red between the connector on the alternator directly to the ignition switch. Not the starter relay/solenoid which is only energized when the starter is cranking.

But you may have another issue unless you missed something in your testing.
All these incorrectly connected wires should keep the coil from sparking. If you have a spark at the coil but not at the plugs then there is something wrong with the distributor.
Check the rotor and make sure the distributor is turning when the engine is cranking.
 
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sprdv1

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All the above.. let us know what you figure out
 
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jimmyk

jimmyk

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You have an incorrect interconnection.
There’s no way a normally wired alternator affects the ignition and there’s no way that a wire from the alternator should be connected to the I wire of the starter relay.
The I wire is directly connected to the ignition coil and should not have anything to do with your alternator.

So do as was suggested and disconnect the alternator, or just disconnect the wires from the I terminal of the starter relay.

What is at the other end of the Green wire? There should only be a Green with red between the connector on the alternator directly to the ignition switch. Not the starter relay/solenoid which is only energized when the starter is cranking.

But you may have another issue unless you missed something in your testing.
All these incorrectly connected wires should keep the coil from sparking. If you have a spark at the coil but not at the plugs then there is something wrong with the distributor.
Check the rotor and make sure the distributor is turning when the engine is cranking.
I'll have to investigate further, but we haven't done anything with the distributor besides remove it and reinstall it. I do agree sure seems like an issue with the distributor.
 
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jimmyk

jimmyk

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I plan on going back later today and see what I can come up with.....will post later what I come up with. Thanks to you all.
 
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jimmyk

jimmyk

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So it turns out that we somehow got it out of time in changing the timing chain cover. It DOES have spark at the plugs. One thing i didn't mention is that we had to pull the distributor since we found metal pieces in the oil pan.....turns out it was 4 broken teeth of the crank gear that couldn't be seen due to the position of the timing gears/chain. obviously we installed a new timing set and ensured the dots were lined up same as before.

But in Paul's response, it makes me question how I have my wiring.... I see that I need to run the heavy alternator wire directly to the battery and not the lug on the solenoid. I'm now on my third Alternator, so I'm not sure if that is what is why or not. Any suggestions are appreciated.

I took pics but can't seem to figure out how to upload them
 

DirtDonk

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There's only one reason you would not normally run the charge cable to the stud on the starter relay/solenoid. And that's if you have already run out of room for it.
Otherwise connecting it to a lug on the relay is virtually the same as connecting it to the battery. The same thing actually, as a few inches of 4ga or better cable between the relay and the battery is not going to make any difference in how well the battery charges.
Not unless the cable itself is compromised.

I'm sure glad you found the broken teeth! Not a common issue, but it sure would have given you fits trying to get the thing to run right.
Removing the distributor is always a finicky operation. No matter how careful you are in re-installing it you always need to re-check your ignition timing because it's so easy to be just slightly off even if you marked it prior to removal.

As you work on it, if you want to run down the wiring connections again just call them out as you have them and we can revisit their functions.
But basically you need 12v at all times on the Yellow w/white wire, 12v on the Green w/red stripe wire only when the key is in the ON position.

Paul
 
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jimmyk

jimmyk

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There's only one reason you would not normally run the charge cable to the stud on the starter relay/solenoid. And that's if you have already run out of room for it.
Otherwise connecting it to a lug on the relay is virtually the same as connecting it to the battery. The same thing actually, as a few inches of 4ga or better cable between the relay and the battery is not going to make any difference in how well the battery charges.
Not unless the cable itself is compromised.

I'm sure glad you found the broken teeth! Not a common issue, but it sure would have given you fits trying to get the thing to run right.
Removing the distributor is always a finicky operation. No matter how careful you are in re-installing it you always need to re-check your ignition timing because it's so easy to be just slightly off even if you marked it prior to removal.

As you work on it, if you want to run down the wiring connections again just call them out as you have them and we can revisit their functions.
But basically you need 12v at all times on the Yellow w/white wire, 12v on the Green w/red stripe wire only when the key is in the ON position.

Paul
Yes, not exactly sure how they got broken but I suspect it was when he had someone else trying to install factory FI from a mustang....said it would pop really bad. Now has an Edelbrock.


I have the green wire from the Centech to the Green/red stripe wire from the Alternator plug both connecting to the "I" post on the Solenoid. I also have the white "I term" wire from the Centech on there as well.

The yellow wire from the plug goes onto the post with the heavy gauge yellow wire that runs to the battery lug on the Solenoid.

It charges fine and I've not really had any issues but just want to ensure I have it wired correctly. I had previously unhooked all three wires from the "I" post and had the green wires connected to one another and left the "I term" wire both on the "I" post , and subsequently off of it and couldn't get it to start or run correctly.
 

DirtDonk

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It’s not right, but well, if it works don’t fix it!

Is the Centech green wire listed specifically for the alternator? You have to be careful because some of the green wires from a harness are hot with the key in the ACC position as well.
Wouldn’t hurt to check that, but if it’s listed for the alternator it should be fine.
 

DirtDonk

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I think there was some confusion about the letter “I” designation.
The I on the starter relay is a completely different circuit from the I on the alternator regulator.
Normally the two never meet except at the origination point at the switch.

But since they are both off of the same terminal of the ignition switch, and both are only hot in the ON position, it should work.
I’m not sure if there is any downside to it other than if you ever try to connect a charge indicator light in the dash.
But for sure include a voltmeter as part of your instrumentation inside.
 
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jimmyk

jimmyk

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That makes sense.......also, I didn't realize my contributor status had expired so I renewed it....lets see if I can post some pics... IMG_4658.jpg IMG_4657.jpg
 

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Broncobowsher

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Hopefully the ballast resistor wire has been eliminated.
Normally adding any load to the "I" terminal on the solenoid reduces running ignition power. With the MSD box that isn't an issue. But in general it isn't good to put anything on that terminal.
 

DirtDonk

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I see another thing wrong. Possibly…
Is this a 95 amp alternator, or a 130 amp alternator?
Your answer will determine whether using that yellow wire from the Centech harness is advisable or not.
If it truly is just that short section of wire between the alternator and the starter relay/battery, you’re probably OK. But even Ford uses 6ga battery cable there is a safety factor in the overkill range.
In theory even 10 gauge can handle 130 A when it’s only a foot long.
But sometimes you just have to lean to the “why take the chance” side.

Looks like you used the yellow wire to power the system instead of the red wire. Is that correct?
If so, what did you do with the red wire?
 

Broncobowsher

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I see another thing wrong. Possibly…
Is this a 95 amp alternator, or a 130 amp alternator?
Your answer will determine whether using that yellow wire from the Centech harness is advisable or not.
If it truly is just that short section of wire between the alternator and the starter relay/battery, you’re probably OK. But even Ford uses 6ga battery cable there is a safety factor in the overkill range.
In theory even 10 gauge can handle 130 A when it’s only a foot long.
But sometimes you just have to lean to the “why take the chance” side.

Looks like you used the yellow wire to power the system instead of the red wire. Is that correct?
If so, what did you do with the red wire?
One of the saving grace parts is the sense wire it tied to the alternator output and not the battery. So under high loads where that 10 AWG wire would be undersized, the voltage drop across it will let the alternator back off the output a bit. If the sense wire were tied back to the battery the alternator output would just ramp up until it was making enough to reach target voltage at the battery.

The sense wire on the battery brings the battery up to full charge faster as it senses what the battery is at and adjusts the charge output for the battery and compensates for the loss in the wiring. With the sense wire tied back to the alternator, the alternator output voltage is fixed but the battery charge level varies depending on the voltage drop of the charge wire.

If you moved the sense wire to the battery, that charge wire will be taxed a lot harder and will truely be undersized in a dangerous way almost every time you start it.
 
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jimmyk

jimmyk

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I see another thing wrong. Possibly…
Is this a 95 amp alternator, or a 130 amp alternator?
Your answer will determine whether using that yellow wire from the Centech harness is advisable or not.
If it truly is just that short section of wire between the alternator and the starter relay/battery, you’re probably OK. But even Ford uses 6ga battery cable there is a safety factor in the overkill range.
In theory even 10 gauge can handle 130 A when it’s only a foot long.
But sometimes you just have to lean to the “why take the chance” side.

Looks like you used the yellow wire to power the system instead of the red wire. Is that correct?
If so, what did you do with the red wire?
Its 130 amp.

I'll have to take a look for the red wire, I can't remember right off.
 
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jimmyk

jimmyk

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Would be the same gauge as the yellow wire.
You can check the instructions but with Centech the red wire connects to the starter relay and powers the vehicle from the battery while the yellow wire is usually attached to the alternator.
But in the standard configuration it runs from the alternator to the fuse panel through the ammeter rather than directly to the battery.
As you have it now, the yellow wire powers the vehicle from the battery rather than the red wire.
I looked and the red wire is on the same post that is being powered by the battery. Im out of town until the 23rd but brought my CENTECH instruction book so can dig into it a little more

So from what I gather, I need to order the heavy gauge Alt kit from WH with the fuse and replace the yellow wire with the new one and run it to the battery?
 

sprdv1

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If it’s as you say, it’s not necessary to have them both there.
However it’s not hurting anything either.
And it’s a safe place to keep it tucked away for any future need.

yeah for sure...
 
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jimmyk

jimmyk

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I appreciate all your help.....hopefully its a non issue going forward. 🙏
 
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