cj's99xjsport

I am having problems with my jeep(obviously). A few days ago me and a few friends went wheelin , and all was good. When we were about to leave I noticed that my voltage gauge was at about 12...not the normal 14. But thought nothing of it because we had be sitting with the Jeep off but the radio and amp on. Well on the way out my voltage went to 9 or not readable by the gauge.

After two jumps (started both times). It would run for about 2-3 mins then just die.(running really rough and backfiring before it did). When my father came to the rescue, he read 8 volts going into the battery from the alternator. Which lead us to believe that it was the alternator....so after the 45 min trying to finagle the alternator out, we had it tested..it PASSED ...twice.
I have already checked all the fuses and they checked out fine , also the dist.cap had no moisture in it.......so what am i missing lol
chris

cj's99xjsport

I am looking now at the fusible link in between the battery and the alternator

Ender

How old is the battery? could be as simple as the battery just can't hold a charge anymore. Unless you already checked it out.

cj's99xjsport

Not the battery , Because the alternator would still try to charge it.

cj's99xjsport

and the battery will still start the jeep , after being on a charger for a few hours

claygrassmann

just cause they alternator passed a test dont mean its good. especially the autozone tests they suck super bad! i had an alt that read about 10v max when on the jeep and i took it to get tested at auto zone and they said it was good i called BS on them and got another alt in there and it ran just fine after that. go buy you an alt preferably not from autozone and install it and if that dont fix the problem return it and look somewhere else for the problem but im puttin my money on the alt. btw im a mechanic, if you brought the jeep to me to work on for that issue thats the second thing i would take a peak at, first being the battery. we always recommend a new batt when you get a new alt because i bad alt can kill a battery

cj's99xjsport

it was at o'reaily......prob the same difference as autozone. I had another alt. from a junkyard Jeep find and it passed as well.

since you are a mechanic ...whats the best way to get the alternator in/out....it was a beach....

claygrassmann

the easiest way i found was from under the jeep you gotta work it around a bit but it will fall out, or you can pull the battery and battery tray but id rather just lay on my back. there really isnt a great way to do it. its just one of them things that makes wrenching a pain in the butt

cj's99xjsport

I am just not totally convinced it is the battery..... But on the bright side I got some great shots of it wheelin , and got some good shots of my "cherokeeforum" sticker with mud on it.

Diesel

Check the diode trios in the alternator, I would also check the output regulator, it sounds like it may not be working in the correct manner. If the battery voltage drops, the regulator senses this, due to it being connected to the battery, and allows more of the field current input to reach the rotor, which increases the magnetic field strength, which ultimately increases the voltage output of the alternator.