Cherokee4x2

Ok, so I have a question about how my xj starts. Since about Sunday, it's been starting not good at all. I have to press on the gas to get it to start. I've been having starting problems for a while now... Ok, so on my home from work last night, my truck started up funny again but this time my voltage was way low, like around 9. And then it died on me halfway home. My dad an I decided it was the alternator. So today I went to the junkyard and got another one. When I went to take off the old one, I noticed that my hot wire was completely burnt through. All the plastic around it had melted and even the clamp was gone. So I got another clamp and cut off off some of the wire and ran it. After the alternator was installed, I jumped it and it showed 14 volts. Then as I neared my neighborhood, it went down to almost 9 volts, and then when I pulled up to my house it died. So we jumped it again and it died again. We kept trying and it wouldn't stay running. So we took the battery to autozone And they said it was dead so I bought a new duralast gold. Put it in and the truck is running around 12 volts or what I called the 1/4 mark. And my check engine light is on. I can still run my stereo and a/c without the voltage dropping. Does anybody have any ideas what this may be?

excess650

Check the voltage at the battery with a VOM (1) with the engine off (2) with the engine idling (3) at 2K rpm and (4) 3500 rpm.

The battery should show 12.8v with the engine off. You should see roughly 13.5 at idle and closer to 14V at 2k rpm. At 3500 rpm it should still be close to 14v. If the voltage contiues to rise above about 14v as the revs increase, the voltage regulator isn't doing its job.

If your voltages look good, check or replace the cables from the battery and be sure the grounds are all good.