Charging system problems
 

Ok heres the deal. I left my key in my ignition the other night and it was turned to the on position.Well i realized i did this when i woke up in the morning and my car had a dead battery. well i decided to jump it. it would start but then die when i unhooked the cables.So i decide i would charge it for the day. It charged and was around 12 volts. My car would start then but when it was running it was only around 11 volts. I would disconnect the batter and the car would die.

So i figured i had a bad alternator i took it off and had it tested. It was only putting out 11.7 volts. I bought a brand new one and tested it and it was putting out 14.1 volts. I installed it and with my car off voltage is around 12 volts and when running voltage is around 12 volts.The voltage stays the same if i let the car idle or drive it for a little bit.The car will die if i disconnect the battery. I have a unorthodox underdrive pulley but i don't think thats the problem.

Anyone have any ideas?

did you check your alternator fuse?

Yes unless there are two

that sucks...dont forget to bring your old alternator back to whereever you got your new one, they recycle those

Where did you get your replacement alternator?
Some batteries just die - and keep failing under load. If your battery is a few years old, you might want to replace that too.

I have read mixed things about running the car w/out the battery (i.e. once it has been started, disconnecting the battery). I have read that the battery acts as a voltage regulator and "smoother" of sorts, and prevents the electronics from being damaged by the less smooth DC generated by the alternator. Not sure how true this is... maybe some others will chime in.

Actually, I went through the fsm and looks like there are two fuses related to the alternator...
a 120A/140A, and a 7.5A fuse

I think if the fuse was blown it wouldn't put out voltage at all. The alternator also puts out less when you have an underdrive pulley but I don't think at idle this would be a factor, its possible but I don't think so. I've also heard about not letting the car run with no battery installed.

If the fuse were blown he would still get the normal 12 volts till the battery dies out. The link between the alernator and battery is non existant thus no 13.5+V thus a quickly dieing battery.

It might be due to the underdrive pulley, I've heard of people buying aftermarket HO alternators that didn't start working till certain rpms so they had to get their idle speed increased.

I know you lose alternator amperage with an underdrive pulley but I didn't think it would be that much. Hopefully a new battery will remedy it.

I bought the alt brand new from checkers.I returned the core at the same time.I have driven my car all day and it has stayed at 12 volts. So it is charging to a point.I went to checkers a little bit ago and had them do a charging system check. It shows on there scan tool that the alt is not charging and there is a problem.The voltage was at 12.3 with the car running.I can rev the engine while in park up till the rev limiter and the voltage doesn't move.That's why i rule out the udp.I am going to have a look at the fsm and back track all the wires going to the alt to see if there a problem there.And find out where the 120 amp fuse is.I want to think the alt is bad but it has benn tested outside the vehicle and it was putting out 14.1 volts
Thanks for the help guys

Another fuse
 

Hi - there should be another fuse - a 10 amp fuse in position number 13 on the fuse block (left driver side under instrument panel - remove door cover - middle row second up from the bottom) This connects the +12v to the combination meter to give you a light for charging malfunction, - you did not say if you had one or not. Unfortunately, this will not make the circuit charge and shouldn't fix the problem. Be sure the fusible link is good.

Well i checked all of the wires going into the alt and they have power so that means that the alt is junk.I have taken it off for the 3rd time and am going to exchange it for a different one. Everyone says that changing the alt is very hard but i think it's pretty easy. I can take it off and put it back on in under an hour.