neonzion

Hello,
This is my second post, in my first post, my jeep wasnt running and I eventually gave up and sent it to a mechanic which replaced the fuel tank, pump, and lines for $800. Im a 18 year old highschool senior earning minimum wage so try to keep costs near zero. Well the jeep runs decent but today i was taking my girlfriend home and the jeep stalls, completely dies. I nearly died in fear and embarrassment. After 1 minute of sitting, it turns of again and runs rough. I drop her off and head home when it stalls AGAIN! After a minute, it starts up and i manage to keep it running for 10min as i head home. Everytime it stalls steering become VERY hard. I do a little research and there are tons of threads but none really answer well.

So I'm thinking its the CPS, dirty fuel injectors, something along the distributer cap, button, rotor, ignition coil or wires, OR the TPS (whatever that is).

Cleaning fuel injectors cost dealers/mechanics $50-300 which i dont have, however I can get a bottle of Gumout Fuel Injector Cleaner for $3, would it be good?

PLEASE HELP!!!

Radi

It's normal for the steering to become stiff when the motor stalls- the power steering pump stops turning.

So...when it stalls, do the accessories (radio, lights etc) stay working?
Can you re-start it right away, or do you have to wait?
Does it stall out sitting idling, or only when driving?


CPS is a possibility- may as well start testing there.
There is a test procedure for your year, basically connecting an AC DVM to the connector coming up from the CPS, cranking the engine and noting the voltage reading while it's cranking. Might have to search a bit to find the exact numbers you are looking for, I forget.... Below a certain threshold the ignition might become intermittent.

I'd also check your fuel pressure, and make sure it's steady, not dropping out. Perhaps the mechanic who changed the pump will do it as a "check up", since you dropped that much cash on a new unit. Some brands are known for early failure.

Also check the wiring at the ballast resistor on the firewall, perhaps bypass it completely just to check it. Might be opening up when it gets warm, wouldn't be completely surprising if your previous pump pulled too much current through it before failing.

You can also test TPS operation (Throttle Position Sensor), Cruiser54 has a write-up specific to your Renix.

And the grounds... particularly that near the oil dipstick, the battery cables (both ends), the C101 connector on the firewall... clean and tight else various nastinesses commence.

Doesn't sound like an injector problem, but if you are wanting to run a cleaner through there, I'd suggest Techron. Or BG products. Or Lucas as a third choice. Don't bother with the Gumout, it's pretty useless. Mostly cleans out your wallet, lol.

neonzion

Hello and thanks so much for replying! Well I looked at the mechanics receipt and he actually flushed the injectors so it can't be that. I will do the tests after school today and tell you how it goes. There is a $30 CPS on eBay for my jeep, i wonder if it's good and I hope it's easy to replace! I will check all grounds and clean the

cruiser54

Spend a few bucks on a meter ($15) before randomly throwing parts at your Jeep.

Here's how to test your cPS.

Renix CPS Testing and Adjusting
　
　
Renix CPSs have to put out a strong enough signal to the ECU so that it will provide spark.
Most tests for the CPS suggest checking it for an ohms value. This is unreliable and can cause some wasted time and aggravation in your diagnosis of a no-start issue as the CPS will test good when in fact it is bad.
The problem with the ohms test is you can have the correct amount of resistance through the CPS but it isn’t generating enough voltage to trigger the ECU to provide spark.
Unplug the harness connector from the CPS. Using your voltmeter set on AC volts and probing both wires in the connector going to the CPS, crank the engine over. It won’t start with the CPS disconnected.
You should get a reading of .5 AC volts.
If you are down in the .35 AC volts range or lower on your meter reading, you can have intermittent crank/no-start conditions from your Renix Jeep. Some NEW CPSs (from the big box parts stores) have registered only .2 AC volts while reading the proper resistance!! That’s a definite no-start condition. Best to buy your CPS from Napa or the dealer.
Sometimes on a manual transmission equipped Renix Jeep there is an accumulation of debris on the tip of the CPS. It’s worn off clutch material and since the CPS is a magnet, the metal sticks to the tip of the CPS causing a reduced voltage signal. You MAY get by with cleaning the tip of the CPS off.
A little trick for increasing the output of your CPS is to drill out the upper mounting hole, or slot it so the CPS bracket rests on the bell housing when pushed down. Then, when mounting it, hold the CPS down as close to the flywheel as you can while tightening the bolts.

　
　
Revised 07-30-2012

Radi

It isn't easy to replace and the aftermarket units have been so-so at best. Some fail before you get the wrenches put away. Test the current one first and see what you have, of course. It may not even be that.
The general consensus is to get the CPS from the dealer even though it costs more, although a NAPA unit might be an acceptable second choice. You really don't want to be stuck alongside the road thanks to an Ebay sensor, and the CPS is one that will leave you dead in the water when it fails.

neonzion

alright makes sense. tomorrow i dont work so i have plenty of time to test. i will post results soon. i hope its not the CPS. i will also see if any stores nearby carry the fuel injector cleaners mentioned. if not ill pick up a $2 can of crappy seafoam or whatever its called, cant hurt. would you recommend any products to clean ground connections? im going to look into where all the connections are but i may need some advice on where they are and how to properly clean them. Actually, i wanted to wash the entire engine bay but im afraid of damaging something

Radi

I usually clean ground connections by scraping off the heavy stuff, then shining them up with emery cloth, followed by a blast of electronics cleaner. CRC makes a good one that's pretty widely available. You can use it on plugs and connectors too.

You can clean up the engine bay, just cover the TPS and alternator with baggies so they don't get soaked. Those are the two items most likely to be damaged by water.

cruiser54

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

cruiser54

Wouldn't hurt to do this while you're at it:

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 making sure they haven’t retracted into the plastic holder, and then 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. Also 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 plug them back in. I do this on every Renix Jeep I purchase or work on for someone else.
Revised 07/23/2012

V8XJDavid

One other thing you might look at is if you have a catalytic converter (many have cut this off the exhaust) it may be clogged with rust and mud if it has ever been in water. My 91 4.0 had a clogged cat and it would stall and sputter and wouldn't accelerate at all. Would idle OK though.