Im trying to fix my 1991 Cherokee 4.0 auto trans that dosen't like to start on it's own. Battery tested good. Starter will spin on the bench. Battery cables recently replaced. On its own, it will crank, but very slowly or not at all. Attach jumper cables and it'll start. I'm kinda at a loss...

 

Check your battery grounds. Replace if bad. I would use an ohm meter to measure resistance from chassis to engine block.

 

I really appreciate your response! Do I just connect a lead to the chassis and one to the block? Is it that simple? Can you tell me what kind of readings I'm looking for/ I do have a nice multi-meter, just not much of an electrician.

 

Did you load test the battery, or just check for voltage? A battery can show 12V but still not have the cranking amps to spin the engine.

 

The battery was one of the first things i went after. I took it to the store (Advance Auto, I believe) and had them test the battery. They used what appeared to be a real carbon pile load tester and it tested good. It's only a group 58 (smallish) battery as opposed to the bigger and more powerful group 34 used in later years but thats the size that they used in 1991. It behaves a lot like a weak battery though...

 

Start by cleaning all of your grounding point. The include both battery terminals, battery to fender, oil dipstick, rear of head to the firewall, 2 on the coil and the mounting area between the starter and the engine block. Also make sure that the wire connections on the starter and the alternator are clean and tight. If your starter is covered in oil make sure to clean that up too. Hopefully this will take care of your problem. Let us know if this helps. If not we can go from there.

 

Thanks for the ideas RTorrez1! Going to go do that right now

 

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Disconnect the battery before doing electrical work / resistance checks.

 

Also check for parasitic drains. There are youtube videos on how to test.

 

Might be the brushes in the starter. If it appears to be the orginial the brushes could have worn down.

 

STUPID QUESTION......

When you attach the jumper cables to the Jeep Cherokee, WHERE are you attaching them to???

Are you putting both the positive clamp and negative clamp directly on the batter terminals ?????

If you are doing it this way and it starts - check the battery terminals and battery posts.

If you are connecting the positive clamp to the battery and the negative clamp to chassis ground .... then do what others are suggesting.

I had a similar issue and took it to a shop ..... they put it on their electrical test machine and it said " low alternator output ". The so called mechanic put both leads on the battery terminals.

Turns out the ground terminal was bad, the cable was actually loose inside the terminal itself.

 

Check the really short ground right off the negative battery clamp.

 

It was the starter. It was worn enough that the battery by itself wasn't enough to turnit over, but with a jump it would. New starter spun right over. Thanks to every one who offered an opinion!