Ok I have this problem from long time in my '92 Z28 and couldnt find an answer to it the car is carb'd and no ac no heater and no sound system and the car always in the store I bought the car since 2006 and star modding it till this problem appeared the voltage reads above 13.8 and as soon as I hit the brakes or barely touch the pedals applying taillights on the voltage drops real bad to lets say around 11s I searched for a solution but no use and now I saw few topics about bad alts and belt size whatsoever there are few things I did and dont know which one effects the voltage to drop I have March pulleys the 3 pieces crank water pump and alt and now returned he water pump and alt pulleys to stock and no use,the ac compressor is removed and couldnt find ac bypass pulley so I ran the tensioner instead the ac pulley I will try to take picture to show wha I mean and I made an order for Powermadter 140amp if my alt is acting up

 

Here is the picture



Yesterday I fired up the car let it warm toke it for spin and get back home after that in afternoon I tried firing her up but nothing and just now she fires up right away is this alt acting up or other problem? Im thinking taking off the crank pulley and putting a stock one

 

Wth not even single post?

 

Changed the alt opened up the taillights changed all bulbs cleaned their sockets and still the same

 

mine drops with the signal light flashes but goes back to normal after there turned off . how does that tensioner work with the belt routed that way ? i'm getting ready to remove my ac also but can't see spending so much money on a wheel an bracket .

 

Its acting up I dont recommend doing it get ac bypass it will remove the stress on the tensioner and the alt

 

ok , i was just oping it was working for ya . i guess i'll buy the damn ac bypass .lol
does your volts go back up after you take your foot off the brake ?

 

 

Yes and here is the good news I've found a wrong wire going out from the alt that supposed to be the volt gauge but it was a 12 volt wire turns on with ignition and searched for any grounds near the box on the driver side and found a ground two wire that hooked to a 7mm bolt by small lope I ran a tester on both of them and hooked one to the alt plug and the other on the 7mm bolt and VOILA problem solved and cutted the 12 volt wrong wire that ws hooked to the alt plug