Intermittent total loss of electrical

[67fish383S]

I am a week into owning a '67 Barracuda FB S 383 4 speed and I've already had a couple of muscle car moments - the kind they warn you about when attempting to daily drive one of these beauties. I have not had a chance to troubleshoot yet, but the symptom seems pretty unique, so I'm looking for ideas on where to start. I know it is not a battery/charging issue. And probably not a starter problem. With the exception of these two events, she has started easily every time and runs like a top.

Yesterday at the pump after filling up, I turn the key and...nothing. No accessory power, just dead. I turned the key back and forth a few times, take a breath, and she fires right up. I assume it is just some funkiness with the ignition switch, that may or may not be an idiosyncrasy with this car that I'm just not used to yet, but probably not a huge concern.

Cut to this morning (technically the middle of the night). I'm driving to work (about a 40 mile trip one way) and about half way here, I am approaching a red light. I had just finished downshifting and I'm coasting up to the light. She goes completely dark. I mean 3:30 am at a rural intersection in the middle of nowhere dark. I have a huge truck approaching from behind. I'm frantically waving my arm out the window, as the light is now green and I just want to avoid being plowed into. The truck goes around and I hop out and start pushing her backward, trying to get her off to the (basically nonexistent) right shoulder from the center turn lane. After about ten feet or so of trying to push and guide her (with manual steering), I notice the interior lights have come back on. I hop back in with her diagonally across the three lanes, and she fires right up. At that point I made the (probably stupid) decision to continue on to work instead of turning around.

She ran fine the rest of the way. It seems like an intermittent connection somewhere in the main power feed. Does not seem to be a problem with charging or battery capacity. The original D-to-C meter runs right where it should. Hoping someone out there may have had experience with similar behavior and have some ideas of where to start chasing this gremlin down.

Sorry if the above was a bit dramatic and/or verbose. I am a little hopped up on goof balls right now. Happy Monday!

 

[rva]

had the same problem it was moisture in the bulkhead

 

[67fish383S]

had the same problem it was moisture in the bulkhead

Huh. Glad I asked, because that is not something I would have thought to look for, and I'm not even sure where to start looking. If you have a minute, could you give me some more detail about the problem and how you solved it? Thanks

 

[rva]

Huh. Glad I asked, because that is not something I would have thought to look for, and I'm not even sure where to start looking. If you have a minute, could you give me some more detail about the problem and how you solved it? Thanks

pull off the engine compartment harness plugs were they are attached to the bulkhead on firewall, inspect the connections it may be moisture or dirty connectors blow out and or clean manually or they have a spray.

 

[grjammer]

I had that happen. I now keep a cheapo volt meter in the car. Measured at the ballast resistor, no volts, wiggled the bulkhead connector wiring and viola, problem identified. poorly seated pin on the ignition circuit. Luckily I was in a gas station parking lot when it went dark.

 

[Kendog 170]

There i amain feed wire that goes thru the bulkhead that is known to melt from bad connection. Here is a link that explains what might be happening and should be addressed anyhow. Read this it may hit the nail on the head.
Catalog

 

[Mattax]

There i amain feed wire that goes thru the bulkhead that is known to melt from bad connection. Here is a link that explains what might be happening and should be addressed anyhow. Read this it may hit the nail on the head.
Catalog

That infomercial has so much misleading info in it I just can't agree with suggesting to look at it.

Lets actually address the problem by diagnosing it.

so I'm looking for ideas on where to start

Yesterday at the pump after filling up, I turn the key and...nothing. No accessory power, just dead.

She goes completely dark.....I notice the interior lights have come back on

So here we have a number of clues that really help out.
With the engine off, the only power source is the battery.
The interior lights draw power though the 'always hot' portion of the fuse box.
The ignition and start circuits do not go through the fusebox.
Additionally, they all have their own ground except they do share the battery negative cable.

Knowing all these things, look for a poor connection in the wiring they all share.
For a fastback, you want a '67 Supplement for the wiring diagram. There also is a colorized an pdf version posted made by one of the members here.
The main circuit and power feeds look like this.

The big black circle represents a welded splice. That's hidden under the wrap and 99.99% of the time is very solid.
Think of it as the power distribution point. When the alternator is running, it too feeds power to this point.
As you can see, all the other power feeds originate from this junction of the battery output and the alternator output.

To your problem.
The connections that are in common are the battery negative cable, and the battery feed to the welded splice.

After checking the connections then check the fusible link. It is an undersized wire (16 ga) and can be damaged by repeated abuse over time.

Since I have a '67 Barracuda, you can use this more specific diagram, assuming the wiring on your car has not been hacked.

 

[67fish383S]

To your problem.
The connections that are in common are the battery negative cable, and the battery feed to the welded splice.
View attachment 1715553215

After checking the connections then check the fusible link. It is an undersized wire (16 ga) and can be damaged by repeated abuse over time.

Since I have a '67 Barracuda, you can use this more specific diagram, assuming the wiring on your car has not been hacked.
View attachment 1715553216

Wow, thanks for the detailed reply. It gives me a lot to go on. Much appreciated!

 

[Mattax]

Here's some photos.
Neg. to engine.

Neg at battery (hopefully not like this) but a common repair type that will cause problems.

Positive feed to starter relay

Fusible link (if original it will have yellow flag)

 

[Mattax]

Bulkhead connector removal.
If you have to do this. Do it when you can take your time.
It requires patience.
If in a rush, do a wiggle check with the door ajar and see if the interior lights blink.
For 67 the battery feed/charge wire goes through cavity Z as shown in photo.


For removing the bulkhead connector without breaking it.
question on the main harness plug on firewall

 

[Mattax]

If you haven't found it yet, then time to go inside.

If you have to remove this one, first remove the bulkhead connector on the engine side.
Then use a small flat tool to release the terminal's locking tab. More about that here Lost all power need help

The two on the back of the ammeter are the most difficult to access. Eliminate the other possibilites first.
Best to disconnect the battery before sticking your hands up there. A ring or any metal contact between the posts and the ground will short the battery and melt the fusible link!

 

[Backally]

Mine did the same thing. Was connector from steering column to harness. Would wiggle when I worked the clutch. Zip tied it up secure and haven’t had a issue since

 

[RedFish]

Mine did the same thing. Was connector from steering column to harness. Would wiggle when I worked the clutch. Zip tied it up secure and haven’t had a issue since

This 67 doesn't have ignition switch or main power wiring in column.
That connector on the fusible link is a known problem also. Pull it apart and find terminals corroded and/or melted away. Some are melted and wont pull apart without destroying the plastic.

 

[mvh]

When I had this problem, it was corrosion in the bulkhead disconnect. Cleaned every pin and socket and protected it with dielectric grease. Worth looking at theo the major electrical connections as well.

 

[gtgto]

Same issue with my car and it was a poor connection at the fusible link plug. Cleaned up both male and female connections and its been good ever since. Before I knew it was the fusible link we got 3 rides home by AAA on the back of a nice flatbed.

 

[kursplat]

I am a week into owning a '67 Barracuda FB S 383 4 speed and I've already had a couple of muscle car moments - the kind they warn you about when attempting to daily drive one of these beauties...

you can DD it, your just going to fix a few things along the way.

 

[67fish383S]

That infomercial has so much misleading info in it I just can't agree with suggesting to look at it.

Lets actually address the problem by diagnosing it.






So here we have a number of clues that really help out.
With the engine off, the only power source is the battery.
The interior lights draw power though the 'always hot' portion of the fuse box.
The ignition and start circuits do not go through the fusebox.
Additionally, they all have their own ground except they do share the battery negative cable.

Knowing all these things, look for a poor connection in the wiring they all share.
For a fastback, you want a '67 Supplement for the wiring diagram. There also is a colorized an pdf version posted made by one of the members here.
The main circuit and power feeds look like this.
View attachment 1715553213

The big black circle represents a welded splice. That's hidden under the wrap and 99.99% of the time is very solid.
Think of it as the power distribution point. When the alternator is running, it too feeds power to this point.
As you can see, all the other power feeds originate from this junction of the battery output and the alternator output.

To your problem.
The connections that are in common are the battery negative cable, and the battery feed to the welded splice.
View attachment 1715553215

After checking the connections then check the fusible link. It is an undersized wire (16 ga) and can be damaged by repeated abuse over time.

Since I have a '67 Barracuda, you can use this more specific diagram, assuming the wiring on your car has not been hacked.
View attachment 1715553216

Update: I’ve been through the entire wiring harness looking for loose connections. I think I’ve eliminated all underhood wiring and the bulkhead connector. The ammeter has already been hardwired through the bulkhead bypassing the connector (done by the previous owner). The symptom has been hard to intentionally recreate, making troubleshooting difficult. All of the underdash wiring seems sound too. When I get it to 'go dead' (it just happens, I have not identified how to make it happen), I start wiggling every wire and connector that makes sense to wiggle, but none have revealed themselves as the culprit.

The only component that seems to be consistently involved is the ignition switch. I want to say I’ve narrowed it down to a loose connector on the ignition switch or the switch itself, but that doesn't fit the symptom. Based on the wiring diagram, I should be able to remove the connector from the switch and still have headlights, interior lights, etc. But after I re-seated the connector on the ignition switch, I haven’t been able to recreate the issue. The ammeter seems to read differently now too (leaning more toward "C" than in the middle). I will probably replace the ignition switch anyway because they are cheap and readily available. Any thoughts? I'm scratching my head.

 

[67fish383S]

Also, I have not been able to identify the fusible link. It looks like it may have been removed??! I can't find it anywhere in the path where it should be, unless it is covered by tape. Unless this is it? Doesn't seem like it would be because it is hard-wired, not easily removable/replaceable.

 

[toolmanmike]

Next time it acts up wiggle the wiring harness at the bulkhead connector. I had a Super Bee that did that. I bypassed that bad connection and the issue was gone.

 

[Johnny Mac]

I had bad connections / cables at the battery terminals, and main grounds, and radiator support grounds act like the above.

People hack all kinds of things between the battery terminals, starter solenoid, Main grounds, as the years go by. Even had the "wrong" size battery terminals vs post size cause intermittent blackout on a car I bought.

 

[Mattax]

Also, I have not been able to identify the fusible link. It looks like it may have been removed??! I can't find it anywhere in the path where it should be, unless it is covered by tape. Unless this is it? Doesn't seem like it would be because it is hard-wired, not easily removable/replaceable.
View attachment 1715554380

Your photo shows correct wiring for a '67.

The fusible link is in the bulkhead connector.
Maybe to see in this photo.

Original

The ammeter has already been hardwired through the bulkhead bypassing the connector (done by the previous owner).

Maybe in this process the link was eliminated. When you have a photo we can see how it was done.
When the factory ran wires to the ammeter through a grommet instead of using the multi-connector they had a couple different ways of handling the fusible link(s).

I want to say I’ve narrowed it down to a loose connector on the ignition switch or the switch itself, but that doesn't fit the symptom.

I agree, but the ignition switches do get worn out internally. I'm just replacing the one on my '67 now but its been on its way out for years. The car has at least 250,000 miles on it so not terribly surprised...
When I check the internal positions for resistance, run had as much 300 ohms depending on how I wiggled the key...

Based on the wiring diagram, I should be able to remove the connector from the switch and still have headlights, interior lights, etc. But after I re-seated the connector on the ignition switch, I haven’t been able to recreate the issue. The ammeter seems to read differently now too (leaning more toward "C" than in the middle).

I agree.
There's two reasons it might be charging at a higher rate. The first simply is the battery is a little more discharged. The second is that increased resistance to the current makes the voltage regulator sees a lower voltage. When the regulator sees lower voltage, all it knows it is to increase the field current. So if the alternator is producing power now at say 15 Volts when before lets say it was 14.5 Volts, the battery will charge at a higher rate.
OK. Three reasons. if the there is a better connection now between the alternator and the battery, less resistance = high voltage seen be battery = draw more current for charging.

 

[Mattax]

Your key probably looks different. The ignition key (maybe switch too) was changed many years before I bought it.

To seperate the lock cylinder from the switch, turn the key to run (or any position other than off) and deperess the brass pin.

I bought a Standard US50 switch (left). Quality seems OK and the positions are correct for '67.

 

[67fish383S]

Next time it acts up wiggle the wiring harness at the bulkhead connector. I had a Super Bee that did that. I bypassed that bad connection and the issue was gone.

Thanks. Been there, done that. No amount of wiggling the connector on either side of the bulkhead has revealed itself as the problem. Connector and pins seem clean and sound.

 

[67fish383S]

I had bad connections / cables at the battery terminals, and main grounds, and radiator support grounds act like the above.

People hack all kinds of things between the battery terminals, starter solenoid, Main grounds, as the years go by. Even had the "wrong" size battery terminals vs post size cause intermittent blackout on a car I bought.

Thanks. I've checked all underhood cables and connections. Everything seems sound and is tight. I haven't as of yet been able to find anything that looks hacked or modded, other than the bypass of the bulkhead connector of the ammeter feed. The pins were removed and a solid wire run through the port.

 

[Johnny Mac]

Thanks. I've checked all underhood cables and connections. Everything seems sound and is tight. I haven't as of yet been able to find anything that looks hacked or modded, other than the bypass of the bulkhead connector of the ammeter feed. The pins were removed and a solid wire run through the port.

I have even seen 1 gauge wire that was cracked/corroded inside....copper doesn't age all that well if any moisture is involved.