ianmgt50

I put a set of bbk underdrive pullies on my 94 5.0 and ever since then my battery wont charge when my headlights are on, anyone else have this problem, or any advice.

makarovboy

I have a 93 5.0 and had the same problem. I bought the powermaster 140amp alternator from summit and haven't had a problem since. It would be cheaper to go back to stock pulleys, as the powermaster for the '94 is listed at $399 for the 200amp. I'm not sure what the amps on the stock one is, but although I kept my pulleys, I don't think they make that much of a difference.

ianmgt50

Thanks alot, I think that I'll look for a cheaper alternator because i have 115,000 miles on my stock one so its probably about done anyways.

makarovboy

Good idea. My alternator internal regulator went bad, that' why the new alternator. I was still experiencing charging problems when the old one was good, but it was only 75amp to begin with. Good luck.

ECR5.0

i had the same problem i just went with the 140amp alt and it was fine. The lights still dim alittle but when you step on the gas is goes right back up. i bought mine rebuilt...and i had no problems and it was alittle cheaper.

93lx50conv

Yea I have a 93 5.0 and i have underdrive pullies on too. When my car is just at an idle my the alt. gauge goes down but when i go on gas a little it goes right back up. I think i want to look for that 140 amp.

Hoaguestang91

Yah my car does the same i have a 91 5.0 lx I'v been looking for this answer for months my headlights just kill my battery stock is 130 amp right? but just 10 mor amps do it? i have a new stock alternator thats y i havent changed it yet unless its absolutly gonna work.

settled4automatic

stock alternator on foxes is 80 or 85A, the sn-95's had 130A alternators stock --- i bought a new 3G alternator and installed it on my 1988gt --- it was around $200 i think. you'll need to do a little wiring, and you can find all the "do it yourself" directions on the internet here : )

67mustang302

That's what UD pullies do, they turn everything slower including the alt. At idle, especially under electrical load, you'll discharge the battery. Even with my Powermaster 140A it still discharges at idle with nothing on but the brake lights(and the engine, duh) but once it gets up over 1,200rpm or so it produces enough amperage to run everything all at once

945LSTANG

Underdrive pulliesare annoying. I removed mine so that i would be able to install a new stereo system. The stereo drained that battery with the pullies on. An amazing stereo is worth more than 5-10 hp.