65 Barracuda - No Charge from Alternator

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MonkeyTrev

MonkeyTrev

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The photo I uploaded is of the alternator off of my Barracuda. I just took it and got it tested and it tested just fine, but when I have it installed on the car I get 12.2V at the battery and it just slowly goes down as the car is running longer. I currently have two wires coming off the alternator one goes directly to the battery (mounted in trunk) and the second ones goes from the male terminal to the volt regulator. I was really hoping the alternator was bad so I could just quickly swap it out and be done, but nope.

Do I need to run a ground wire from the terminal circled in red ?
should I run new wires from alternator to volt regulator and so on ?
I currently do not have a ballast resistor on the car, but would that really affect the alternator charging ?
All help is wanted, nothing is really stock 65 barracuda anymore, MSD Distributor, MSD Box, MSD coil

Barracuda Alternator .jpg
 
No it grounds thru the block. Do you have power to the field wire at the altenator when it’s running? I’m guessing you don’t.
 
sounds like a points type regulator failing. They turn on and off with actual points.
 
If the alt tested good, then it is most likely the voltage regulator (VR).

With the engine running check for voltage to the bottom terminal of your VR should be battery voltage. Next check for voltage at the top terminal. It should be 6 to 10v if the regulator is working properly, battery voltage if it has failed closed, 0 volts if it has failed open ( most likely)

you should double check that you have a good ground to the VR.
 
I divide these problems into "areas" No particular order
1...The charge (output) circuit. This is the big black wire, connects to the stud, carries the main output through the bulkhead connector, through the ammeter circuit, and back out to the battery. THIS IS NOT FUSED

2...Field wiring circuit. This is known also as "IGN1" I call it "ignition run." Comes from the key, comes out into the engine bay, and (depending on year/ model) feeds the ignition sysem, and the VR. On newer cars it feeds the alternator field (70 and later) and feeds electric choke and or smog devices if equipped. THIS IS NOT FUSED

3...One single green wire goes from the VR F terminal to the alternator F terminal

3....The alternator itelf
4.... The VR

A "quick test" is to clip a meter to the alternator output stud and run the engine at fast idle. "Rig" a jumper wire from the battery, and after pulling loose the green field wire, feed battery power to the alternator F terminal. This should cause "full output" and the voltmeter should rise some.

If it rises not at all the alternator is not putting out
If it rises WAY high, maybe 18 -20+ volts or more, the charge wire/ ammeter circuit has problems
If it rises "some" up 15-16V it is charging "at least some

Next, Reconnect wiring, and now disconnect VR wiring. "Rig" these and jumper them together. Rerun the test. If altlernator is good and all wiring is good it should now charge--you have bypassed the VR

If this test shows OK replace the VR. Make CERTAIN that the VR is GROUNDED. Clean/ scrape the bolt holes on the firewall and on the VR flange and mount using star lock washers.
 
SGBARRACUDA said:
No it grounds thru the block. Do you have power to the field wire at the altenator when it’s running? I’m guessing you don’t.
Click to expand...
I just started the car up and when touching the field terminal on alternator it showes 3 Volts on it. I can see those same volts on the VR and then I test the opposite side of the VR it varies between 3 volts and 11.5 Volts.
 
I am barely getting any Voltage off of my Field wire, somewhere around 0.4-1 on my multimeter.
 
Apply twelve volts to the field wire while its running , with the volt meter hooked to your battery. It should charge wide open. If so its your VR.
 
OP had alt tested. It tested good.

The 3 volts out if the VR is suspect the 3 to 12 v into the VR is also troubling.

I would jumper from the battery to the input of the vr. That way you have a for sure 12v going into the VR. If you still have only 3 volts going to the field of the alt. Then you have a bad vr. If you have 6 to 10 volts going to the field then you have some issue with the voltage being supplied to the vr.
 
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