After reading through the archives, and in need of an alternator upgrade, I find this GM 105 amp how-to and figure "hey, if it worked for him, why shouldnt it work for me?" So i go out and buy everything i needed, a proper plug.. a '92 GM delco CS130, it all fits together.. bolts into the car alright, put the belt on.. it looks fine and dandy.. but then to see if the alternator will do its job....

I don't think so.. I wire it up exactly like the how-to says so..
Sensor wire to the output post, B+ wire on the output post, and the L wire to the rx7's L wire, and it should be good to go.. Thats what I thought... but i start it up to see its charging UNDER 12 volts, around 11.. everything does in fact work worse then it did before, and all my warning lights stay ON all the time.
I dont know whether the alternator is bad or not.. but when I bought it, it had been tested....

I figure whatever, cut my losses and put the stock back on.. but noo, I had to resize the V belt pulley and fan to fit the GM alt, and now the hole is too big to fit the stock shaft and it wobbles around, so now I cant even use my stock alt with my stock pulleys.....

I checked and re-checked that everything I did matched the how-to.. and it did, and im still stuck with no alternator and down $150..


can anyone see what I did wrong? if anything?

 

Did you check the voltage from the alternator output with a volt meter?
Did you check grounding continuity?

Could be a bad internal regulator or wiring. The alternator is obviously not performing as it should. I would take it to a Autozone or Advance and they will test it for free, then double check all your wiring with a volt meter. A manual with a factory wiring diagram should also help.

Good luck

 

hey there, thanks for the reply..
I tested the alt with a voltmeter while running and it showed about 11 volts. which is crap...

maybe ill take it in and have it tested like you said

 

This is my first post here, and first day I found this site. Been here about 7 hours today!

Athough I can not say exactly what your problem is, I can say with the correct alternator it should work if the alternator works.

The GM/ AC Delco 1 wire alternators are used allot for hot rods and generators.
You only need to spin them and excite the fields and they simply work!

Here's what I do. Get a good alternator $20 or less at junkyard here, ground the case with the mounting and run 1 heavy wire to the battery, spin it with a 12hp riding lawn mower engine, I excite the fields for a second and it's charging up my 12V battery bank of about 1,000 amphrs.

So if you can mount it on your engine and spin it, it should be working.
Exciting the fields on my generator is simply touch a clip on wire from the field post to the battery hot wire, that turns it on to charge.

On a car it would be wired in somehow to do that, but if your getting 11V then it's doing something and the field should be excited. Don't give up on the alternator plan, just find the problem.
Could be a bad wire, could be a bad brush in the alternator? It works if all is correct, so first step maybe is have the alternator checked!
Don't get suckered into buying a new one, mostly a $1 brush is wore or stuck, or a $10 rectifier bridge is burnt etc... Normally if the bearings are good it's a cheap repair you can do yourself.

I use allot of Wind and Solar power for charging battery banks and build 12V generators this way also as a fall back power source.

 

Bingo! The low output can really only be two things:

1. Alternator is bad
2. Alternator is not getting proper ground.

I beleive the alternator gets its ground from the engine while mounted. If the alternator checks out good, I would try adding some engine grounds.

 

Back from the dead!

Sorry, i had to, this is the exact problem i have run into, not 2 minutes ago. i've searched but can't find an answer, sooo...

What was the resolution to this problem, or does anyone else have any new ideas?

the only difference between the OP's situation and mine is that my GM style alternator is an 140 amp model. And its new.

I have 11.5 - 12 volts at the battery, reads less on the dash gauge, seems the alternator won't 'turn on'

i have 11.5 - 12 volts at the stock L lead from the car, idk if thats supposed to be like that.
With the car running, i pull the positive lead off the battery and it dies, so no alternator.

what am i doing wrong?

 

something is wired wrong...the car shouldn't die if you disconnect...

 

yes i know it shouldn't die, but my alternator is wired as per the following:

B+ terminal connected to Positive terminal on battery
L lead on plug connected to stock L lead the was previously connected to stock alternator
S lead on plug connected to B+terminal and in turn, the Positive terminal on the battery
F lead on plug not connected
P lead on plug not connected

Is the sensor wire (S lead) seeing too high of voltage to output anymore? Seemingly not because the lights/blower motor cause voltage drop on the dash gauge.

Does the L lead need to have less then 12 volts on it to turn the alternator on?

Should i do some kind of ritualistic sacrifice to the spirit of charging circuits?

i'm willing to try anything that may work.

 

From another page
http://www.bzerob1.com/tech2/csupgrade.html

all the way at the bottom the note mentions connecting the stock L to the F terminal on the alternator.
is this a bad idea? i don't know enough about the internal workings of an alternator.

i don't want to short anything

 

well ialso ran into this about an hour ago. my alt is charging around 11 volts at idle, but when the revs go up its about 13-14 volts. i think it might just be a slipping belt, but what else should i look for?
\

 

oh wai, i forgot i was in the 1st gen forum.... its hard having 2 cars... hahaha. this is for my TII

 

i'd think the belt would make more noise than electrical variations, maybe the voltage regulator is going out.

 

ugh. well how do i check it? im supposed to drive out to cleveland sunday....

 

go to advanced auto or autozone and have them check the alternator.

i'm not saying its not the belt, just 14v seems a little high to me, and if the belt was slipping
i'd think it would do so under the stress of acceleration
not at idle so much. if the belt is loose enough to slip at idle, you'd be able to grab it (engine off!)
and slip it yourself.

besides if its loose, tighten it. easy fix.

on a side note, if the belt was slipping when you rev the engine wouldn't it show low voltage, from not turning fast enough/evenly?

the voltage regulator should do just that, regulate the voltage. seems like its not.
but then again these are older cars, the amount of fluctuation you are seeing might be acceptable.
someone else should chime in on that cause i'm not sure.