low voltage problem. help!!

[gwmcgowa]

I have an 89 mustang lx 5.0 and I am having low voltage problems. I have replaced the stock alternator 3 times and tried 3 different batteries and the voltage at idle rarely passes 11.8 give or take a tenth. This causes the car battery to lose all voltage and the car shuts off and needs to be jump started. once its jumped, it will run alright until i shut it off again or it dies, and then it will need another jump start. Any input?? I just ordered a 140 amp alternator to see if that helps and i will be buying a new bigger battery as well.

I can give more details about the accessories I am running if need be.

If i upgrade the alternator and battery and the low voltage still remains, what else might the problem be?

 

[MustangBill87]

You need to check out the 3-G alternator conversion thread at the top of the 5.0 Tech "Technical thread list" get a 130 amp alt. for 95 5.0 stang and follow what the thread says to do.

 

[gwmcgowa]

I actually just bought a 140 amp 1 wire from summitracing, from my understanding the only difference between this and a 3g is that for this one to be activated the RPMs need to reach 1200. Is this the case? or should i revoke my order and get a 3g?

 

[MustangBill87]

The 3-g will activate at 750 or 800 rpm and be able to power everything on your car at that rpm, you would be able to sit at idle with 14.5v

 

[gwmcgowa]

as compared to what with the 1 wire?

 

[HISSIN50]

Did you have the system tested? Were the alts bench tested? That will be the only way to know what's going on.

 

[gwmcgowa]

The first alternator was bad so i replaced it, the second one was good but the problem still remains so i just ordered a bigger one.

 

[gwmcgowa]

ps. i have a working aod on my car right now id get rid of. i have another one i am repairing that has a shift kit and stall conv so i wont need this one anymore. its stock

 

[gwmcgowa]

FYI i replaced the alternator today with a 1wire 140 amp and the problem was fixed, car runs like a dream again! thanks for your insight