1999 Cherokee 4.0L stock

I just changed the rad, thermostat, water pump, and hoses. Now the Jeep starts hard. Turns over fine but sometimes need to crank 5-6-7 times or more to get it to fire.

Once warm it seems fine but while idling at 650-700rpms the battery gauge goes up and down between 8-14 volts whenever the A/C compressor comes turns. (does this normally turn off and on with the heater on)? Seems it turns every 3-4 seconds and when it does the battery gauge goes down to 8 volts. As soon as it goes off, back up to 14 volts...?

Seems to drive fine when heated up but wondering if I need a new battery or could it be something else? Cleaned battery posts but no help. Could it be the serpentine belt too tight/loose? Not a mechanic so appreciate any help....

 

If you have a ride I would call around and see if anywhere would test your alternator.
Take it off and have them test it, I would also get the battery tested. To me it sounds like low batt voltage and/or bad alternator.

 

Absolutely check the serpentine belt for the proper tension.

The voltage gauge in your dash should not fluctuate like that. Should be steady at around the 13-14 volt range.

Be sure that all battery and alternator connections are clean and tight. Freshening engine grounds is NEVER a bad idea.

Still happening after verifying above? Have a parts store test it.

 

About to junk this XJ! Went to get gas this AM and after filling it up It wouldn't start.. Jumped, still no start. Turns over fine but will NOT start. Also, when I turn the ignition to "On" the battery and gas gauges don't come off zero... Shouldn't these gauges move?

I had it towed into Monroe Muffler (my bad).. They seem clueless, suggesting I replace plugs and wires, sending unit possibly, fuel pump possibly.. Does any one have an answer for this Jeep? Can't afford a new vehicle right now.

 

Because you have a no-start and a fuel gauge that isn't working, job #1 if this were in my garage would be to TEST the crankshaft position sensor! It is a very common failure on the 4.0

If you have a bad crank sensor, you will NOT have spark and you will NOT have fuel going to the fuel injectors. The fuel gauge and the voltage gauge may not work properly.

A good shop should be able to tell why it isn't starting. I'm not sure Monroe Muffler is that shop though....hard to tell as a shop is only as good as their technicians.

Testing should tell if you have a SPARK problem or a FUEL problem. Or both. Once you know the answer to that, the suspect list gets a whole lot shorter.

If crank sensor checks out (absolutely MUST test that before moving on) pull a spark plug, keep it attached to the plug wire, ground the spark plug electrode on a good engine ground, have a buddy crank the engine while you watch. You are looking for a strong, blue, snapping spark. Yellow/orange/white spark indicates a weak spark which may not be strong enough to start the engine.

If spark checks out, try spraying a small amount of starting fluid or some gas into the intake. If the engine starts and runs momentarily, you have verified a fuel delivery problem.

The above two tests are critical in determining the ROOT CAUSE of your problem.

 

The mechanic at Monroe Muffler finally found the problem after $500 of replaced parts... One of the three plugs on the PCM harness was corroded and causing a short. They replaced the $245 harness free since they already had me for $500 worth of parts, (Plugs, wires, rotor, dist cap, etc).. But they only did it AFTER some very loud and heated objections on my part. It was a good catch by the mechanic though so I flipped him a $50 tip..

PS, thanks for all the help and suggestions!

 

Well you got a nice tune up! LOL

 

Also It might have been costly, but Im sure it would have cost more for you to figure it out being it was a pcm plug.

 

Yeah, there's NO WAY I would have EVER found it!