'89 3G upgrade still has low charge

[89_LX]

I upgraded to a 130 amp 3g alternator from PA performance and the cars carge is still barely above the red zone on my gage.

for the installation I cut the plug with the 2 black/orange wires and one white wire, taped off the 2 black wires and ran a 4guage wire from the alternator to the starter relay, and added the provided connector to the white wire. then plugged in the other factory plug

I do have underdrive pulleys but my stock 75 amp charged just the same with the pulleys as the 130 amp

Is there something else I am missing or have overlooked?, also the charge at idle does not get any better at higher rpm,

 

[SuperStang83]

You might want to hook up a good gauge since the stock ones aren't always so accurate.

 

[93 LX]

underdrive causes the alternator to turn slower thus causing a lower charge at idle. Also did you change the ground strap on the engine? More amprage means a wider path is needed.

 

[89_LX]

No i did not change any ground wire, are you talking about the wire that goes from the ground battery post to the block? or is there another ground wire i missed

 

[LarsD]

No i did not change any ground wire, are you talking about the wire that goes from the ground battery post to the block? or is there another ground wire i missed

Go to the parts store and look in the "help" section. There should be some wire braid
straps on the rack (flat strap). I usually try to run one from the point where you bolt it to the block and then onto the frame.

 

[HISSIN50]

At higher output (higher alternator RPM) is where the extra ground pathways really shine, unless one has deficient OEM ground cables.

I'd agree with measuring things with a DMM. Note idle voltage vs voltage at 1000 engine RPM vs 2000 RPM. Then see how it does with a load. If the only time it sucks is at idle (notably warm idle), consider speeding the alternator up.

Good luck.

 

[jtfairlane]

Is this an Automatic car? Auto's will experience lower voltage at idle, even from the 3G, than a stick.

You can purchase and install an Overdrive (not underdrive) pulley for the 3G that will help keep the voltage up at idle no matter what, and will be especially helpful if using an underdrive crank pulley, which is slowing down your alternator pulley. The faster the alternator pulley spins, the better it will charge.

 

[Big Top GT]

Before you buy ANYTHING, you need to properly diagnose the problem.

Typically, when you have a bad alternator you have other problems. Either the alternator kills the battery from the constant/under charging, or a bad battery kills the alternator from constantly needng to be charged from nothing.

I'd recommend you take the car to a local PepBoys and pay them 20 bucks for their electrical system diagnosis. They test the system with the battery in the car so you'll know what's wrong.

It's cheap and will save you a LOT of headache.

Once you know what's wrong, then you'll be able to buy the right part to fix it.

Personally, I think it's a bad battery.

Good luck,
Alan

 

[89_LX]

I Ran the car for a bit today and its not charging at all, im only running underdrive pulleys on the crank and water pump and using the factory pulley on the alternator i also noticed today that the battery/amp light was on. the battery is only about 3 months old

 

[HISSIN50]

If the amp light is on, there's an alt issue. Check your wiring connections. Ensure the stator circuit has continuity and that the sense circuit is still intact.

Then If that's all copacetic, have the alt bench tested.

 

[89_LX]

Sweet, i started checking wires around the solenoid and found an out of place wire that was going into the opening for the washer resevoir, bolted it to the solenoid, started it up and found a healthy charge, i knew i was missing something stupid,

thanks for the help