HELP, won't start!

[drase]

When I turn the ignition there is a slow whine then constant clicking but the truck won't start. Just to make sure its not the battery I charged it overnight and still the same problem this morning. Could this be the alternator?

[skidoo_j]

Assuming the whining sound you hear at first is your fuel pump then the clicking is the starter solenoid. Even though you charged the battery overnight it could be:

 

A totally dead battery that did not take the charge, - take a multi meter reading and see if resting voltage is above 12v.... have someone turn the truck over while you measure, does it go way way down? Have someone jump, connect the negative on your engine not on battery.

 

It could also be the starter solenoid, sometimes whacking it a few times will get it out of a dead spot.

 

 

 

The alternator would not be a possible for not starting. it could be for not charging the battery, but not for starting. Starting is battery, starter, ignition switch if not turning over. If turning over and not starting cps (at fly wheel), wires at stator, distributor, coil, fuel.

[nhrocker]

First thing I would check is the group of grounds on the side of the block where the dipstick tube is bolted on. Remove the bolt, clean well, and reinstall. My own MJ did similar to what you describe, I started throwing parts at it, just to find out all it needed was the grounds cleaned up, which was free and only took a couple minutes to try.

 

If that doesn't make a difference in starting, next I would check the lead from your battery to the starter. They are notorious for failing in MJs/XJs. Even if the ends look fine, the wire inside the insulation can become dry, brittle, or corroded and fail. You can try wiggling the ends of the wire while someone tries starting it, or easiest way I've found is to use one lead of a set of jumper cables. Clip one end directly to the battery and then the other end down to the nut where the end of the wire connects to the starter. If it starts then you just need a new power lead and/or battery terminal.

 

Other easy to check items that could cause issues like this are the main grounds to the battery. Make sure both ends of all the grounds are clean and in good shape, especially the one going directly to the block, as it's the one that would most likely affect your issues.