motowill594

Thanks in advance for everyone's help !

Ok my jeep keeps dying on me and I'm out of ideas it seems like I've tried everything !
The worst part is it will run perfect sometimes then all the sudden it will just die ! Somtimes it will start right back up and other times leave me stranded in the middle of a intersection !
It's a 1990 cherokee I-6 auto here's a list of things done in attempt to fix the problem

New cps (2)
New tps adjusted properly
New cap rotor champion copper plugs
Re-indexed ditributor
Tried ecu out of a 1989
Coil and map sensor
Cleaned throttle body and iac
New fuel pump and filter tested at about 31 psi
Compression between 145-150
"Heet" in gas tank in case of moisture.
Anyone have some ideas

Bigwillie

check all your grounds. and well while your checking them might as well clean them up while you are there.

KJamesJR

Have you checked your ground wires?

KJamesJR

Damn... that was a coincidence.

FishinXJ

What do you do to get to to start after it leaves you stranded?

cruiser54

Start with this. Takes less than an hour and costs $20 if you go all out, which I suggest.

Have you ever checked the CPS output, even on the new ones? Seen them weak right outta the box.
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

cf1k1

Your terminals on your battery. I had the same problem. Replaced the starter and it started right up. Next day, dead. Replaced the terminals and the flimsy 16 gauge wire. Positive wires replaced with 4 gauge and both grounds replaced with 2 gauge.

SeriousOffroad

Try duplicating the problem in your driveway. With the engine running, start wiggling evry harness/wire that you can get your hands on.

If it dies you've then got a place to start looking at.

cf1k1

This too. I had to do the other way to get it started!

Ian96XJ

My upstream O2 sensor's wiring had insulation that was breaking apart underneath the loom. Every once in awhile, the two wires would touch and short out and cause my Jeep to just die and not restart. Look for bad wiring, especially under the looms.

motowill594

Ok thanks guys I will try the things everyone suggested

Also I have checked all grounds but have not replaced them !
And as far as getting it to restart nothing is ever consitant .but it does smell like its flooding sometimes and if I pull a sparkplug wire to check for spark it will usually start right up and run on 5 cylinders I've tried wiggling every wire

MI_Offroad

Try wiggling the oil pressure sending unit, the plastic case can crack, slightly move and the wires inside short the engine out.

Drove me nuts till I found it.

DFlintstone

I saw that sometimes you smell gas, still this test is too easy. If you can catch it when it has just died, turn the ign off, (right away!), then depress the little Schrader valve on the fuel pressure port and see if it spurts a little fuel into a rag. No spurt=fuel problem.

It's a 90? Does it happen to be a manual trans? (clutch material can affect the CPS) I see it's your third CPS, still you can check it in literally seconds with a digital meter. Simply unplug it, and check for about 1/2 volt AC coming off the two leads to it while you are cranking. Intermittent stalling and no-starts are a hallmark of that cridder. (my 90 started giving me trouble when it got down to about .3 Ac-V

You can wire brush (any/all), relay connectors, spray out the socket's with electrical cleaner, apply dielectric grease...or at the least, swap the fuel with the AC relay, (it does more than just the pump), see here> http://autorepair.about.com/library/images/bl347lib.htm

And one more! There is a ceramic resistor on the inner fender by the air cleaner. Power needs to get to, (the front), and through it to get to the pump. You can check/clean those connections, or even just by-pass it. It's mostly there just to quiet the pump a bit.

cookrw

Same here, both my terminals were bad and it would run perfectly for a while and then randomly die. Sometimes it would crank right back up, and others, it would appear that there was no power at all. I replaced both terminals and ran a new ground cable from the negative terminal to the body. Runs great with no problems now

motowill594

Ok so I cleaned the grounds up again today and took it for a test drive and again it died on me so I did what "Dflintstone" said and depressed the schradder valve right after it died and NO fuel came out just air ! Then cranked it over again and it fired right up checked the valve again and this time fuel came out ! So I take its a fuel delivery problem ? Again I put a new fuel pump and filter in and it tested good !


Any idea where I should start looking ?

Could this still have something to do with bad grounds or bad fuel pressure regulator

What would cause air in the fuel rail ?