Sometimes when I go to start my jeep it cranks really slow like the battery is dead but eventually it builds up alittle momentum and starts. Other times it doesnt start at all and I have to jump it. This happens completely random normally its when its sits for awhile like over night but not every time though which doesnt make me think it is a dead battery or a bad alternator because if that was the case it would do this everytime I shut it off. Plus when I get in the Jeep all the interior lights work and so does the radio an stuff unlike when your battery is dead and nothing works. Im not sure if it the starter or not. Its always took alittle while to turn over but it would crank fast like it should for maybe 5-10 seconds then fire up. its progressively gotten worse but it still starts, never more than 10 seconds though. I havnt changed any of the electrical components such as new lights etc since a good month before this problem started.

 

Similar thing happened to my 1991 XJ.
Was the starter. After replacing only the starter it cranked fast (normal).

 

I figured it would be the starter, is that a hard fix

 

It's easy on the 4.0
2 bolts and the wires.
Be sure and disconnect negative on battery first!

 

Could possibly be a bad battery/ground/starter connection.

 

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any suggestions on brand? I'm assuming acdelco Bosch denzo would be atop the list

 

In my opinion, whatever you trust / like. Whatever you do, make sure the one you get has a lifetime warranty, and it should be fine

 

I just finished putting in a new not reman prostart from pepboys and went to start it up and almost same problem, it started it 3-4 cranks but it sounded weak and they were slow cranks so I shut it off restarted same thing the second time except the second time the rpms went to 2k and started climbing slowly up to 3 so I shut it down again and came out about 15min later fired it up still sounded weak but fired in about 4 slow cranks and idled fine I'm pretty clueless what the problem is now battery terminals look fine and so did wires that bolt to starter

 

Take it to pep boys and have them test the battery and alternator. Or take it to whatever parts store that will do the test for free. It's abad idea to start parts replacing electrical problems, try to do some testing or have it done first, it'll usually save you money.

 

yah im going to run some tests tonight after I get out of class. Its weird because I drove it a couple times today and it randomly will start perfect, good turn over speed and turn over in 3 cranks and other times it sucks. Drive time and time the vehicle is sitting make no difference on how it starts. I thought maybe it just needs broken in like calibrated with the computer system in the car and I remember someone saying there was a way to reset your computer somehow by like putting the key in on position and turning the high beams on etc but i cant remember how to do it

 

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This.

For intermittent problems like this, you gotta start with connections. Basics first always before replacing any component.

1. Remove battery cables from battery. Clean all until shiny and reattach.

2. Have your battery "load tested". Any parts store will do this for you for free. Load testing is the only conclusive way of determining battery condition.

3. Freshen ALL engine grounds. Marginal grounds are the root cause of many electrical issues. More on grounds below. Never ignore grounds!

4. Verify starter connections are solid and that you don't have significant voltage drop between the battery and the starter with a meter (which could indicate a bad cable).
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Grounds can be the root cause of many electrical gremlins. Refreshing grounds is NEVER a bad idea, and the investment of your time in this procedure is always well worth it!

You can't tell much of anything by looking at ground connections!! You must remove, scrape, clean until shiny the cable/wire ends and whatever they bolt to. Be sure to remove all paint from any ground connections.

Start with the one on the back corner of the head, and where it attaches to the firewall, as it deteriorates over time and is an area that makes it susceptible to damage. Best to replace that woven cable with a #4 or #2 gauge cable. You can attach the one end to the intake manifold if you would like.

Next go over to the engine dipstick tube stud. Remove the nut and clean the wire ends and scrape the block until shiny at the stud. Reattach tightly.

If you are so inclined, add at least a #6 cable from the negative terminal of your battery to one of the bolts on your radiator support.

 

I went to advance auto and got my battery starter and alternator checked out on their diagnostic machine. Everything read good but he said the battery could used charged like on a trickle charger over night but other than the the alternator was reading proper volts, no battery draining anywhere, and the starter was working as i excpected it would considering its brand new haha. But of course when I started it up for him to the diagnostic it started fine no problems but oh well.

The spark and ignition system is what Im about to go out and adress tonight, I picked up some dielectric boot grease and a tool to remove the spark plug boots from the spark plugs because I was pulling and twistin them every way possible and they wouldnt budge and plus they put the boots on these 4.0's in such tight to reach spaces like below the a/c compress its tough to get my hands in there. Gotta love the 4.0 haha

Now if the fueling system wasnt functioning properly wouldnt the car run bad? Because once its started it runs perfectly fine no problems. And if any of the sensors in the PCM unit were bad it would through the CEL right? Because my check engine light isnt on

 

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