Kris smith

Ok I have a 90 4.0 I just put a 220 amp alt in with Kelleys wip 1 wire ga cables and 250 amp fuse kit. And it won't charge at idle. I'm at 12 v flat AR idle. Do a alt test with a vat 40. It puts out 235 amps and 14 volts at 3500 rpm. But noting at idle. Any ideas the guy who did the alt build said it needs a smaller belt.

toasterknight

You need a different pulley to make the alternator spin faster.

Kris smith

It has a 46mm pulley on it he said it needs a .5" shorter belt

toasterknight

Unless the belt is slipping it is not the problem. The problem is the alternator is not spinning fast enough at idle to produce enough amperage.

Kris smith

It's tight. No sloping slipping causes noise I don't have any. I'm going to try the smaller belt

toasterknight

It's going to nothing but cost you money. The problem is the pulley being too big.

Kris smith

I feel that if I go any smaller on the pulley I will need the smaller belt.

Kris smith

I have a 1 7/8 pulley on it now.

freegdr

Thats smallest you can get.

Kris smith

Well then looks like I may be ****ed. Unless the belt for some reason helps. I'm going to get it once I can find one. If that don't work I'm having him take the thing back.

sycoglitch

What brand is the alt anyways and why did you go specifically with a 220 amp

Kris smith

It's from a guy who runs Js ultimate alternators. He builds custom ones mostly for the stereo and low rider guys. I asked for a 200 or more alternator and he's aid he had a 220 for the jeep in stock. The 100 amp isn't enough to run my lights and jeep and heater/ac as it is. And if I wanted to add more stuff like a winch or something later on I felt it would be needed. The the Kelleys cable kit came with a 250 amp fuse kit so I couldn't really go above that