Prezents

Hello all than thank you for your input.
I have a 87 civic with a 1.5 and it has carb
I started having some issue's with the battery just going dead. I thought that the alternator was going out so I replaced it... Needless to say that the old one tested good as well as the new one that I had put on it
It is strange. I have a volt meter that I can plug in the cigarette lighter and I can monitor the voltage. As soon as it start it, it will jump up on fast idol, and it is charging 14+ volts. as soon as I kick it off of fast idol it will drop to less that 9 volts.
I am at a loss here. any help would be appreciated.
Thank you again.

Prezents

and when it comes off of fast idol it runs rougher, I am sure that this is due to it not charging.

antihero12

ok im not 100% sure on this but check your negative wire on your battery. it could be causing ground issues if its not grounding out out right. For example my dad has a 2000 dodge ram an if its not grounded right, the truck wont even start. so like i said just check your battery wires. maybe thats the problem maybe not lol

Prezents

I went as far as using a die grinder with a wire wheel on it to clean the motor ground point. and cleaned up the terminal posts as well....

antihero12

hmm im at a lost then sorry wish i could help more good luck though

Sera_

The manual suggests to check the main fuse and the fuse box for blown fuses, and the tension of the alternator belt, but I guess you've been there a hundred times now. If it's any help, here's the alternator wiring diagram:

Prezents

You are correct, I have been over every fuse with a multimeter and a test light, inside under the dash and the small one on the passengers side strut tower.

Prezents

?????? ??

Sera_

I would definitely place my bet on the regulator, but since it's built into the alternator, and you already bought a new one and tried that, it can't be it. This is a real mystery.

letank

So when you turn the ignition on, before cranking the engine, how much voltage does the battery have? It should be very close to 12.56 volts -ideally-

At idle it is almost normal for the alternator not to be charging because the engine speed is so low, but it should be close to the battery voltage of 12.5v, basically you are using the battery.

You can go to your local parts store, Kragen now O'reilly, or Autozone, and they do free checking of your charging system/battery, so you do not have to replace good parts. I am not too hot about autozone parts, they have a high rate of failure, even with the lifetime waranty when someone borrows you vehicle and they get stranded 4hrs away, they are still stranded....