When my 1987 Jeep Wrangler is cold, and at an idle the tac stops working , and the ammeter shows a negitive charge, and then the belt squeals. Once it warms up it seems to correct it self for the most part, The Tac will only go to 2500 before it begins to jump around. Is there a colation between the charging system and the tachometer. The problem with the squealing belt begn after the lights were left on and the battery died.

Check your belts and pulleys. Belts should not be cracked and pulleys should turn freely with no noise.

wrangler? YJ? 4WD"?
what engine, what fueling system. Carb. or EFI?
2.5 L AMC 150 I4 Complete engine specs[show] 4.0 L AMC 242 I6 Complete engine specs[4][show] 4.2 L AMC 258 I6 Complete engine specs some 87s have a carb. does yours, (nobody can fix enigine not kwowing both facts above and what transmission,.


stalls , moving, only. at stop lights or between gears.
but never just parked idling.
if its random , that would be the EGR valve sticking open.
if EFI , bad idle switch.
if Carb bad dash pot. on carb.

belt can be old and when itis getting older rubber mateiral used in belt hardens. when it hardens it slips especially whne air is cold and humid.
replace it. (if it is an old piece, you will see vertical cracks on it but it can serve but if there are parallel cracks to belt sides it is bad)

if belt is not old, you need to tighten screw next to power steering pump and pulley. when you find pump puley you will see the bolt used to tighten.

When the belt starts to squeals, its time to replace it. over time the belt will streach and get glased over. 9 time out of 10 replacing it will stop the squealing...1 percent....you may have to replace your belt tensioner, along with your belt.....
Hope this helped you ??

try idle air sensor

look for a weak tensioner ,or a bad belt,one or the other,or both are your problem.

I would suspect the crank sensor, but it needs to be verified when it wont start.

banjo tight 1/8 deflection with 5-10 lbs of pressure

I have a book with the whole electrical, haynes repair manual has the diagrams . 1987 thru 2003.I have 1987 wrangler with some issues. How would I get you infobook 50030


l

hey

Its possibly the belt!!! did you change that to?

Damien