I have some issues on my 86, n/a, It seems to be stalling when I let off gas, and so during stalling voltage drops up to 12v from 14.1. so my question was is the alternator what causes stalling or is a cause of the stalling?\

then I was test driving it and while driving @ any rpms the voltage was sitting at 12v.
So I took it to autozone to test it and it pass 2 out of 2 times.
Also i've check battery, belt tension , terminals, and I know is not the voltmeter because i have an aftermarket and both read same.
ANy help is apreciated.

 

Anything under 12.5 volts and the car is running on the battery. The voltage needs to be at a minimum of 13.5 volts to charge the battery and ideally should be at 14.4 volts anytime when running for the best spark and power.

If the alt is not putting out sufficient voltage, either the voltage reference wire to the alt is hooked up improperly or the alt is bad or your alt belt is slipping (and belt slipping is highly unusual at idle- so if it is a problem at idle you can generally rule out the belt slipping).

 

my cars been running at 12 v even since i got it.. its been my dd for about 6 months now. Dam i thought 12v was normal.. its runnin on a walmart battery. Im gonna take a look at the alternator now..

 

Does the stock gauge tell you 12v? Mine sits at about 12.4 but it's not accurate.

 

Is is safe to assume the problem is around the alternator?

Because I did some more test driving and saw the voltage drop right after the engine stalled.

 

The voltage dropping when the car is off is fairly normal. Mine does it. You should test your alternator.
Alternator Testing

 

I did test it, took it to the autozone and passed 2 out of 2 times

 

Yeah, screw Autozone. Do it the way the link says.

Then do it the way the FSM says if you really want a good test.

 

Check the battery voltage as a baseline, then check the voltage at the battery with the car running. If they are both normal it's probably not your alternator. I'd check for vacuum leaks first and go from there.

 

Your battery can be low without it being an alternator problem. My battery sits at about 11.5v when my cars off. It's been that way for years now regardless of what I do. It's just an old crappy battery, but it gets the job done.

 

well I just tried the link and then couldn't get a stable number, as soon as I turned it on the engine started stalling. Mine idles usually at 2k rpms, ( I have it that way) and so it stalled up to 300 rpms, thats when the voltage drop from around 13v to 12v the it came back to 2k for a second then goes to down upto 300 rpm and back and foward.
when the engine is at those very low rpms is shakes like crazy but it doesn't turn off. I have tried giving it gas and raise it up 4 or 5 k rpms but as soon as i let got it keeps stalling to 300 but just doens't turn off on its on

The battery voltage while is off is 11.8. Is alwayz been that way
Voltage while on was around 12.5

Im beginnnig to think this isnt a alternator problem due to the stallling

 

I knew there was some reason I've never taken an alternator to the autostore to have it checked out. This post is proof positive of why to Not take a alternator to the autostore.

 

Measure the resistance between the alternator casing and the negative battery terminal as well.

 

OK now is it really safe to assume alternator, because I was driving @ normal mph for about 15 min while it was at 12.5v, then I startet to notice the brightness of my head lights and saw the voltmeter and it was at 10v, so about a mile from home rushed to get there and the voltage was dropping.
When I got home it was @ 7v. then I was checking voltage at alt. and batt. and were about the same. I let it on for about 4 min before slowly started to got down until it turned off.
Try to crank it and no nothing just as my battery wasn't charged(duuh)
Should I go for a new alternator??

 

You have a shorted cell in the battery or have a bad meter then

 

Autozone tests the alternator by spinning it... if it spins it must work.

Do not buy a Autozone alt... 2 out of 3 of them are typically bad from the get go.

 

Should I replace mine then

 

It's been tested with 2 different meters and if I have shorted a cell it's not causing me any problems.

 

You guys think I sholud replace the alt??????

 

I have ran/started a FC with two dead shorted cells (8 volt battery) before just fine.

 

I would

 

i would say if you can an alternator thats in very good condition then go ahead and try it out, if thats the problem then it would easy fix it and if not then you've got a new alternator that'll last you longer then your old one! my cars been havin some issues with that as well so im thinking about buying a bosche alternator online

 

Botch alternators are just rebuilt ones... you would be better off buying one of the Mitsubishi ones if you can get it. The extra $20 or $30 is well worth it.

Ideally when buying a alt, you want a Remanufactured alternator, not a Rebuilt one. Rebuilt ones have all the non working parts replaced, while remanufactured have any part that can fail replaced.

See the difference?

 

oh really? i didnt realize they were rebuilt, my friend offered me his mitsubishi alternator off his old engine, i guess ill just stick with that then, or get a newer mitsu one

thanks icemark

 

Yeah, you could just have a crappy battery, but having a crappy battery puts more strain on the alternator. And yeah, voltage drop would be a good thing to check while having this problem.