1st Generation Specific (1979-1985) 1979-1985 Discussion including performance modifications and technical support sections

Stock alternator problems?

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Old Oct 21, 2017 | 02:35 PM
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From: myob
Stock alternator problems?

Hello, I've got an 82 with a rebuilt streetported 12a. Currently running a holly blue with a Mikuni 44phh. Everything seems to be fine except that I don't get enough power (electrically). With the lights on, the car drops rpms, pump changes tone and the radio hardly works, so I think the alternator just doesn't provide enough power maybe, why would it not? The only things it needs to power are the old cassette radio, lights and pump, I can't imagine the pump would suck that much power away. I just wired the pump up to the same wires the stock one was wired to and it all seems to work fine, except for that. Did I do anything wrong? I think the blue is overkill and I should have gotten the red, but I'm not really sure, I only got it cause it came with the FPR.

Any ideas? Thanks alot
Old Oct 21, 2017 | 02:45 PM
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Take the alt off and take it to the auto parts store for testing.
Old Oct 21, 2017 | 03:14 PM
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And when you take the alternator to be tested, if it doesn't fail right away, have them do an extended test.

My GSL-SE was having issues charging its battery. After all the troubleshooting tests, I diagnosed that the alternator was bad. I took it to a shop for testing that specializes in alternator rebuilding but it passed. After a lot more troubleshooting with no results, I finally gave up and sent the car to my mechanic. He diagnosed a bad alternator, took it to the SAME shop and got them to do an extended test and it finally failed.

Moral of the story: don't assume a part that passes a test is actually good.
Old Oct 21, 2017 | 07:19 PM
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Test alternator on car... take it to a shop that does electrical work and test complete electrical system alt,starter,battery with an adjustable carbon pile load tester. Check system voltage running with accessories on. I have seen more false"good and bad"tests from auto part stores alternator testers,personally don't bother with them. Op car may have alt problem,and or voltage drop issues from old wiring,questionable connections.
Old Oct 21, 2017 | 07:53 PM
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From: myob
Well thanks, I'll take it to a shop and see. Do you think maybe it could have been the wiring harness? For the rats next delete, I just went and clipped all the wires at the connector that weren't being used and then I wrapped it back up. The only things I have going now are the alternator wire and ground, the temp, oil level, coolant level, and oil pressure sensors, and whatever that one is on the water pump housing. Is there anything I could have clipped on accident that would have messed it up?
Old Oct 21, 2017 | 08:49 PM
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Alternator has output wire which goes to main fuselink. Should have a field plug on back with two wires. These wires are black/white and blue/white I think. The alternator needs these wires to initiate charge and turn on battery light on dash when not charging. A simple test...turn key to on and note all warning lights at bottom of gauge display,is the battery light on with the rest? Does it turn off with others when car is started? If so alt is charging. Take a pic of alternator showing wire connections to it and post here so we can get a look at it.
Old Oct 21, 2017 | 08:54 PM
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The wire on back of water pump housing is for temp sensor for choke magnet that pulls choke **** in when engine coolant reaches correct temperature.
Old Oct 25, 2017 | 12:13 PM
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Originally Posted by pepsuchan
For the rats next delete, I just went and clipped all the wires at the connector that weren't being used and then I wrapped it back up. The only things I have going now are the alternator wire and ground, the temp, oil level, coolant level, and oil pressure sensors, and whatever that one is on the water pump housing. Is there anything I could have clipped on accident that would have messed it up?
This sounds terrifying, what did you wrap these wires up with? Electrical tape?
Old Oct 26, 2017 | 11:30 AM
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One other suggestion, if your alternator checks out OK.
Are you using the original wiring for the fuel pump? When I put in my Carter, the pump would change its tone when I used turn signals and other electrical draws. This was even with a T2 Alternator.
I ended up using the original wiring to trigger a relay that then supplied power directly from the battery(don't forget to put a fuse inline) and it now receives a consistent amount of power no matter what I'm doing.
Old Oct 28, 2017 | 04:02 PM
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Originally Posted by DreamInRotary
This sounds terrifying, what did you wrap these wires up with? Electrical tape?
Yes, then I covered it with some of that flexible conduit. The original wire harness was wrapped this way as well. What else do you guys do, just let those 7-8 useless wires dangle around?

Originally Posted by SunRedRX7
One other suggestion, if your alternator checks out OK.
Are you using the original wiring for the fuel pump? When I put in my Carter, the pump would change its tone when I used turn signals and other electrical draws. This was even with a T2 Alternator.
I ended up using the original wiring to trigger a relay that then supplied power directly from the battery(don't forget to put a fuse inline) and it now receives a consistent amount of power no matter what I'm doing.
Yes, I just connected the pump to the original wires underneath the car. I might do this, thanks for the advice.

Originally Posted by GSLSEforme
Alternator has output wire which goes to main fuselink. Should have a field plug on back with two wires. These wires are black/white and blue/white I think. The alternator needs these wires to initiate charge and turn on battery light on dash when not charging. A simple test...turn key to on and note all warning lights at bottom of gauge display,is the battery light on with the rest? Does it turn off with others when car is started? If so alt is charging. Take a pic of alternator showing wire connections to it and post here so we can get a look at it.
I'm pretty sure I left those connected, the light on the dash test passes and I do know that it charges the battery, I've been driving it for quite some time now. Actually, I'm pretty sure it was the battery maybe that was causing this issue? I found out that the battery the original owner had put in was a piece of crap and not even the right size, so I got a proper one. Now my starting issues seem to be gone and so is the problem with the electrical. Before, the voltmeter would dip under 12 volts and now it stays above it, the radio works fine, the only thing is that the pump changes tone to the turn signal, so I might try that suggestion from the previous quote.

also here's the pic you wanted, I'm not sure if this helps. I just noticed that connector is still here, but I've forgotten what it could have went to, probably something with the original nikki

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Old Oct 28, 2017 | 06:55 PM
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It would appear to be charging properly. Very good idea to put a relay in pump circuit to isolate it from other systems in car. Wired this way,pump will use less current and work better. Likely to hear a difference in tone/speed of pump.
Old Oct 28, 2017 | 08:35 PM
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Originally Posted by pepsuchan
Yes, then I covered it with some of that flexible conduit. The original wire harness was wrapped this way as well. What else do you guys do, just let those 7-8 useless wires dangle around?
Personally, I delete the entire section from the harness. I take the harness out of the ECU (in a 12a it's barely that) and delete each and every individual pin from the harness, and take the entire wire out of the system. This way I know that there won't be a short or an issue due to electrical tape failing.

Another tip, buy 3M electrical tape. I only use it now, once you've torn a piece of 3M tape by hand compared to the cheap multi packs you'll understand. Once I found this out I will never use the cheap stuff again.




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