Ranger 4.0L Running Problems... HELP!

[prerunner32]

Ok... so hear it is. my ranger has been sitting a little and has a weird symptom. put new batteries etc.. did normal maintanace to get it running good again. When the truck is running on its own, if sputters like its miss firing and runs insanely ruff, smoke comes out of the exhaust.... just not good. But when on jumper cables to a F-250, it runs perfectly fine. Then take off the cables and back to crap.... What is wrong!!!!!

Thanks

Alan

[bigtex]

Sound like you need to check the charging system. Do you have a volt gauge? if so what does it read? If not then get it started by itself and grab a voltmeter and see what it is at the batteries, if it is below 13.0 or so go to the back of the alternator and check voltage there. This is where I would start.

[manicmechanic]

Definetly check voltage running, also charge the batterys up good and run it with the alternator disconnected. Sometimes a bad alternator can throw voltage spikes and radio freqency interferance into the system and drive it and you nutz.
Another thought is if you are running the jumper cable ground to the block like the guy from the insurance company says, maybe a shaky ground cable.

[DSRacing]

Definitely check and make sure you have good solid ground connections.