So I have a 1990 Cherokee laredo and I'm havin an issue.. I just recently got this vehicle and it worked fine though the starter was acting up a bit... You would have to turn the key once and then a second time before it would start up. It was driven a half dozen times or so and then the last time it was driven it didnt want to start at all. It was towed home and I replaced the starter since the old one tested bad. I tried to start it with the new starter installed but it still would not start up. I took this starter back to Oreilley's and had them test the new one twice and it tested good. We checked the battery and charged t to make sure it was good (it is a new battery). We replaced the starter relay and still no start. The thing is that the engine begins to turn over for a few seconds but about half way through the cranking, it instantly stops and you just hear a noise that is similar to a power antenna humming, which I haven't been able to locate the noise's origin. I've checked for bad fuses and have checked the neutral safety switch and every seems to be good... Also, the wire from the starter to the relay splits into 2 separate wire and I notice that when I disconnected the second wire, the engine turned over for a much longer duration, but still didn't completely turn over... What the heck could be the problems?? Help please someone!

 

Your battery cables and connections are probably dirty. Remove them at each end and clean them up nice and shiny.

Here's something else you should do:

Renix Ground Refreshing
The Renix era XJs and MJs were built with an under-engineered grounding system for the engine/transmission electronics. One problem in particular involves the multiple ground connection at the engine dipstick tube stud. A poor ground here can cause a multitude of driveabililty issues, wasted time, failed emission tests, and wasted money replacing components unnecessarily.
The components grounding at the dipstick tube stud are:
Distributor Sync Sensor, TCU main ground, TCU "Shift Point Logic", Ignition control Module, Injectors, ECU main ground which other engine sensors ground through, Oxygen sensor, Knock Sensor, Cruise Control, and Transmission Sync signal. All extremely important stuff.
The factory was aware of the issues with this ground point and addressed it by suggesting the following:
Remove the nut holding the wire terminals to the stud. Verify that the stud is indeed tightened securely into the block. Scrape any and all paint from the stud’s mounting surface where the wires will attach. Must be clean, shiny and free of any oil, grease, or paint.
Inspect the wire terminals. Check to see that none of the terminals are crimped over wire insulation instead of bare wire. Be sure the crimps are tight. It wouldn’t hurt to re-crimp them just as a matter of course. Sand and polish the wire terminals until clean and shiny on both sides. Reinstall all the wires to the stud and tighten the nut down securely.
While you’re in that general area, locate the battery negative cable which is fastened to the engine block just forward of the dipstick stud. Remove the bolt, scrape the block to bare metal, clean and polish the cable terminal, and reattach securely.
Another area where the grounding system on Renix era Jeeps was lacking is the engine to chassis ground. There is a braided cable from the back of the cylinder head that also attaches to the driver’s side of the firewall. This cable is undersized for it’s intended use and subject to corrosion and poor connections at each end.
First off, remove the cable end from the firewall using a 15mm wrench or socket. Scrape the paint off down to bare metal and clean the wire terminal. Reattach securely.
Remove the other end of the cable from the rear of the head using a 3’4" socket. Clean all the oil, paint and crud from the stud. Clean the wire terminal of the cable and reattach securely.
A suggestion regarding the braided cable:
I prefer to add a #4 Gauge cable from the firewall to a bolt on the rear of the intake manifold, either to a heat shield bolt or fuel rail bolt. A cable about 18" long with a 3/8" lug on each end works great and you can get one at any parts store already made up. Napa has them as part number 781116.
A further improvement to the grounding system can be made using a #4 cable, about 10" long with 3/8" terminals at each end. Attach one end of this cable to the negative battery bolt and the other end under the closest 10mm headed bolt on the radiator support just forward of the battery. Napa part number 781115.
For those of us with Comanches, it’s very important to remove the driver’s side taillamp assembly to access the ground for the fuel pump. Remove the screw holding the black ground wire. Scrape the paint from the body and corrosion from the wire terminal. Reattach securely.
If you want to upgrade your grounds and battery cables in general, contact Jon at


www.kelleyswip.com. He makes an incredible cable upgrade for a very reasonable price.
　
Revised 03-04-2013

 

Thank you very much for your input I will look into these suggestions an see if they my be a help... Might I also add that the vehicle is turning over strong, it isn't like it has a weak or dead battery. And the terminals are clean as well...