Alternator meter is jumping around and the lights are dimmed... won't stay running

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supersoap33

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I have 74 duster with a 318. Just put the intake back on. I don't remember the gauge jumping like this all the time. Voltage regulator is pretty new and the wires going to it look okay. It's also firing out of the carb if I try to gas it, but it runs okay for a few moments and then dies as the gauge goes crazy. Alternator was working fine before I put the intake back on. What could it be?
 
Dana67Dart said:
Did you reconnect all the block to body grounds
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I'm not certain where those are! I just took off the whole intake because I left the country and the car was in a high crime area and then reconnected it when I got back. Where are these grounds at? I know of the one going from the negative post of the battery to the body. What else is there? Pics would be helpful!
 
"Basics" Battery main large cable MUST ground to the block. From block to body there needs to be MINIMUM of at least one no10 or larger, OR from battery NEG post to body. There can be more

I would get it running and get timing set THEN worry about charging. If the battery is a "good" one and charged, it should run the car just fine with NO alternator for quite awhile. In other words you should be able to disconnect the VR connector and it should run fine.
 
But if no body ground things will ground through any path.

There might be one by distributer to firewall. Or as noted earlier. From battery negitave to rad core support.

I agree the engine running then died. If the engine was running too slow the ammeter would bounce and lights could be dim.

I would check for grounds AND get the engine running reliably before worring about the ammeter bounce
 
Or maybe pinch a wire in the process!
 
Could also be the brushes in the alt. They do wear down & fail. Just a coincidence that it did it at this time.
 
67Dart273 said:
"Basics" Battery main large cable MUST ground to the block. From block to body there needs to be MINIMUM of at least one no10 or larger, OR from battery NEG post to body. There can be more

I would get it running and get timing set THEN worry about charging. If the battery is a "good" one and charged, it should run the car just fine with NO alternator for quite awhile. In other words you should be able to disconnect the VR connector and it should run fine.
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It is running. It runs until it depletes the battery, and while it's running, the volts jump around on the gauge, so the alternator isn't working or something.
 
supersoap33 said:
It is running. It runs until it depletes the battery, and while it's running, the volts jump around on the gauge, so the alternator isn't working or something.
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This does not make sense at all In your previous post you said "runs momentarily."

A car with a good and with a charged battery (old, non EFI) should run HOURS on a battery, and I have done it. If you are running down the battery just running the car in the garage, either some serious wiring problems or junk battery. I'll say it again........you need to fix the engine problem then worry about the alternator

There is one other possibility, and that is you have a terrible situation with your bulkhead connector, as an example. Try "hot wiring" the ignition and see if that improves the engine run situation. That is, jumper 12V from battery direct to the "key side" of the coil ballast, or the "key side" of whatever other system you are using.

What experience do you have? You fairly checked out on wiring, do you have a service manual, and what have you done to try and torubleshoot the overall problem of the engine run proboem or the alternator problem?

When was the last time "it ran right" ?
 
MAYBE you have some short going on instead of an open. Try figuring out how to isolate "stuff" from the problem

EG you can pull the wiring loose supplying the car interior as well as the alternator. Start with the starter relay. Remove the wiring from the "big stud" on the relay and follow the one going from there to the fuse link to the bulkhead connector. Leave that off, put any others back. Now check for power at the altenator stud. Should be NONE. Check for headlights. Should NOT work.

Now to run car, remove the "key side" wire from the ballast and jumper power to that. To start car, jumper across the two exposed terminals of the starter relay. This should get you "starter" and "ignition" to run the engine and nothing else. Will it run? Is it stable, act "right?" If not fix it.

Then reconnect wiring and figure out.........are you "losing" a feed connection (open/ poor connection) or do you have a short happening? (pulling down voltage). Is there wire smoke or smell? Hot plastic?
 
Check the large ALT (black) and BAT (red) cables at the bulkhead connector. They often melt. Search "MAD Bypass" for many posts.
 
BillGrissom said:
Check the large ALT (black) and BAT (red) cables at the bulkhead connector. They often melt. Search "MAD Bypass" for many posts.
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I deleted the bulkhead connector because mine was fucked anyways. It ran fine without it until I pulled the intake manifold. This is all happening after I've replaced the manifold. I just installed a new distributor and now the temp gauge goes all the way up before the engine is even running and it won't stay running. I hate this ******* car. I just want it to ******* run for christ sakes.
 
Yep there is a reason I call electrical "voodoo". Best to pay close attn and follow the instructions to the elec gurus on here. Good luck.
Trace your bulkhead wires, make sure they're good and connections are solid.
 
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