Frickin' XJ starts but won't run... any ideas?????

Last thursday I was making my normal 30min commute to Franklin, TN from Murfreesboro where I live. On the way up, my check engine and check gauges lights come on and the voltometer is dead, reading 9volts. I pull over, with it still running, listen and look under the hood and everything seems fine.
That night as it would be parked, it would idle over 1k rpm with slight surging. as if it was trying to charge the battery.
Friday morning I'm driving to work and the windows are extremely slow rolling up and my head unit, which is turned off, keeps flashing the screen on and off. My digital odometer gets really dim just as if the alternator is going out.
From here I figured the alternator died and the jeep had been running off of the optima red top battery. Autozone tested my alternator and said it was reading 14.5-15volts but the internal bearings could've gone out.
They said it could be a fuse. I've been told it's prolly the computer. I've also been told there could be a bad ground somewhere. Does anyone know exactly what could possibly be going on?!

If I were you I'd take the alternator somewhere else and re-test it. I had a similar problem before I got my Snap-On Charger/Diagnosis equipment. When I took the alternator to Autozone....I had the same readings as you. Well...I knew it had to be the Alternator.....so...just for fun....I took the alternator to everywhere (Autozone/Advance-Auto/Napa/Rodefelds..etc) w/in a 25 mile radius of me. I had them all test it....for a total of 5 tests. Guess what? No 2 tests were exactly the same....but 3 out of the 5 tests did read around 11...to 11.5 so...I replaced it and solved the problem. I guess what I'm saying...is sometimes the slightest change in how an employee hooks up the alternator to test it can make a difference...even w/the wiring kits they now have to test them with. I had 1 guy @ Autozone test the alternator 3 times....with 3 different results!!
Don't dive into the nightmare...of guessing/wiring/computer related troubleshooting just yet. I would advise you to have it re-tested....and while there...talk them into giving you a series....say 3....of tests...and average those.
Just my .02 cents worth
Aron

thanks aron! I'll def give it a couple more tries... too bad the old alternator is back on the heep. oh well. and while reading your response, I remembered that the guy at autozone was hesitant at wiring it up, like he was pretty unfamiliar with the machine.

would you mind telling me exactly what your jeep was doing when the alt went out?

Exact same thing happened to me a few weeks ago. I could jump start and it would stay on as long as it was in 'park' and i had my foot on the gas, but as soon as you put it in 'drive' or turn on radio/lights or anything it dies.
Also, just so you know we had the same problem, my lights and radio just died on me one day while I was actually driving. Electric doors and windows wouldn't work. I had just had a new battery installed so it wasn't that, its that nothing is getting the power and electricity to the rest of the car. That's the alternator not working.

That's what it was for me, sounds like the same for you. You can take it out yourself and get it tested, or have it towed and tested at auto zone pep boys etc. But good chance is you'll need a new one.

Hope this helps.

Thanks man. That little voice inside me yesterday said to go ahead and put the new one on. Grrrr....

toymachineracing said:

Thanks man. That little voice inside me yesterday said to go ahead and put the new one on. Grrrr....

Click to expand...

time to get the high-output one for your premium power welder anyway...

I'm sorry man. Just don't push it off a cliff, I know you didn't mean it.

Dude, give me a holler sometime, if you can get the beast out here, you can use my garage. hehe. Or if you need help just give me a call.

'preciate it blake.

what's a good alternator run? what's a good brand?

I've heard of Powermaster and Mean Green alternators and Starters. I know the Mean Green one is about $360, so it must be worth it if its that expensive. I don't have either, but those are two names to search for.