You might try this also. When refreshing the relay receptacles, move the relays one place over from their original location.

I suggest unplugging EVERY electrical connection in the engine bay you can find, whether engine related or not, and spraying it out with a good electronics cleaner, visually inspecting the terminals, and adding dielectric grease before plugging it back together. There’s a critical 10-pin connector for the front lighting system located in front of the air cleaner and behind the left headlight assembly. Don’t miss that one. Be sure that the connectors to the ballast resistor mounted near the air cleaner housing are clean and tight.
ALL of the relays should be removed, the terminals wire-brushed until shiny, and the receptacles sprayed out with contact cleaner. Then dielectric grease should be added before plugging them back in. I do this on every Renix era Jeep I purchase or work on for someone else.
Revised 07/15/2012

 

I replaced the fuel ballast resistor and I still have no luck keeping the car running. It is still starting on a dime but after a couple of minutes it cuts off.
Should I replace the fuel pump regulator? fuel pump? Not sure. Please help!

 

I replaced the fuel ballast resistor and I still have no luck keeping the car running. It is still starting on a dime but after a couple of minutes it cuts off.
Should I replace the fuel pump regulator? fuel pump? Not sure. Please help!

 

You could but no way to tell if it's gonna fix anything. Just a guess without testing. Have you done any of the other things I suggested. If I were gonna speculate on something, I'd do the free stuff first.

 

Not all of the things sir. In my haste to resolve the problem, I have replaced the fuel pump, fuel pump filter, fuel ballast resistor, and fuel pump regulator and as you can guess I still have the problem. I went back and read posts and sprayed electrical cleaner to connections. I could not find the "critical 10 pin connector". Perhaps that will make a difference. It still starts then cuts off. Please advise.

 

The critical 10 pin connector near the air cleaner is for the headlights and parklights anyway. So what exactly have you done which I advised?

 

Evening Cruiser-when it cuts off does it start right back up?

 

Did you test the CPS using my write-up? Evening freegdr...

 

When it cuts off, it cranks back up with no problem. It just doesn't stay on. I spray every electrical connector in the engine bay (that I could find) with electrical cleaner. I DID NOT use the dielectric on the connectors. After I moved relays one over and tried it and no results. I moved back the relays and no results. I use to stay on longer before all of this. Now it cranks up and stays on about 30 seconds. But it does crank back up without a problem.

 

Well it doesnt matter too much if it starts right up if it dies a few seconds later. I just kinda skimmed thru the thread but saw a no start and i saw you were adviced about the crank sensor.. i didnt read thru it... but i didnt see were you actually said u replaced the crank position sensor? In my experience the cps is the culprit in 99% of xj no starts or dying not long there after. Its very possible u could have got a bad one.. they arent cheap($100) so i hope u kept ur reciept and exchange it out give it another try. If that doesnt work xj's dont like bad grounds clean all those retighten. Might be the computer also. I was gonna say, remember, a good mechanic is a lazy one, but it seems like you have already thrown alot of parts at it... so scratch that. Hope u can get it figured out soon.

 

I have replaced a lot of parts. However, its an old vehicle. Eventually they would have needed to be replaced (at least that's what I say to myself to keep my sanity). I did replace the CPS and it started fine and I was driving it. This latest episode happened when I was driving on the freeway and turned on the air conditioning and it started to loose power. It haven't recovered since. That's why I approached the fuel system. With that said, I still have the start but cut off issue. Since I have replaced major parts of the fuel system, perhaps this may be just a wiring or relay issue. Not sure.

 

Have you ever done the ground refreshing or ICU to coil contact refreshing?

 

Not sure how to do ground refresh or ICU to coil contact refresh.

 

We have the technology to overcome that problem:

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, and wasted money replacing unnecessary components.
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.
　
　
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 11-28-2011


Renix Jeep ICU/Coil contact refreshing
　
　
The contacts between the coil and the ICU on your Renix Jeep can become corroded and loose causing a complete or intermittent no-start condition. I recommend the following procedure as a maintenance precaution to insure this is eliminated as a possible cause now and in the future.
The coil is attached to the ICU by two T20 Torx bolts. Remove these two bolts and lift the coil up off the ICU. You will see 2 pins and 2 sets of contacts. Clean both the pins and springy contact pieces with a good electronics cleaner.
Squeeze the springy contacts closer together with some needlenose pliers. Apply some dielectric grease to the contacts and bolt the coil back on to the ICU.
While you’re right there unplug the connectors from the ICU and inspect the pins in the harness connector. Make sure the pins are not retracted into the connector. Spray out the connector and the receptacle of the ICU with the same good electronics cleaner you used earlier. Apply dielectric grease to the connectors and plug them back in.
I feel this procedure should be performed at least once in the lifetime of a Renix Jeep.
　
Revised 11-29-2011