stev-o

my jeep is cranking wen i turn the key but it wont start i have fuel at the fuel rail and im pretty sure i have spark
it does take a couple seconds to start wen it starts anyway why does it take so long

i have replaced my cap an rotor and plugs
i have had a few probelms in the past but it started an ran fine after i checked for fuel and spark but it doesnt seem to be that easy this time

stev-o

i dont know y my jeep just wont start out of nowhere

DFlintstone

Hey there Steve. Well, I'm posting a few of Cruisers writeups here. Course you don't have a C101 connector, but really I think you want to do the CPS test. Make sure it is on the low AC scale, unplugged, cranking well. Also anyone with a Renix probably would benefit with the coil as well as the grounds cleanup.


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 it’s mounting holes with the first drill bit that just won’t fit through the original holes. Then, when mounting it, hold the CPS down as close to the flywheel as you can while tightening the bolts.
　
Revised 11-29-2011


Renix Ground Refreshin
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.







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
************************************************** *****************************

Renix Jeep C101 Connector Refreshing
　
The C101 connector on 1987 and 1988 Renix Jeeps was a source of electrical resistance when the vehicles were new. So much so that the factory eliminated this connector in the 1989 and 1990 models. The factory recommended cleaning this connector to insure the proper voltage and ground signals between the ECU and the fuel injection sensors. We can only imagine how this connector has become a larger source of voltage loss and increased resistance over a period of almost 25 years. The C101 connector needs to be cleaned at least once in the lifetime of your vehicle. Chances are it’s never been done before.

Almost every critical signal between the engine sensors, injectors, and the ECU travel the path through the C101.
The C101 is located on the driver’s side firewall above and behind the brake booster. It is held together with a single bolt in it’s center. To get the connectors apart, simply remove the bolt and pull the halves apart. You will find the connector is packed with a black tar like substance which has hardened over time.
Take a pocket screwdriver or the like and scrape out all the tar crap you can. Follow up by spraying out both connector halves with brake cleaner and then swabbing out the remainder of the tar. Repeat this procedure until the tar is totally removed. This may require 3 or more repetitions. Wipe out the connectors after spraying with a soft cloth.
If you have a small pick or dental tool tweak the female connectors on the one side so they grab the pins on the opposite side a bit tighter. Apply a true dielectric grease, not the stuff that came with your brake pads, to the connection and bolt it back together.
　
　
Revised 11-29-2011

tjwalker

Pretty sure won't cut it. For a no-start, the FIRST thing I do is verify spark.

You are looking for a strong, blue, snapping spark. Yellow/orange/white indicates a weak spark, which may not be strong enough to start the engine.

If you have a GOOD spark (and only if), then try a bit of starting fluid into the intake or a splash of gas. If the engine starts and runs momentarily, then you have confirmed a fuel delivery problem.

And the things that DFlintstone noted are excellent procedures for you to perform, even IF they are not root cause. They will prevent future problems.

stev-o

could a gummed up nss switch cause my jeep not to start also it does crank but it wont fire up

fishtaconc

My advice... Try the above posted suggestions (DFlintstone, tjwalker). The NSS wouldn't allow it to turn over period. Random guessing is reserved for when all other troubleshooting options fail.

stev-o

i went down today an my jeep started up but then died on me while i was just driving it around the block
so i do have spark
an fuel but how come my fuel system only runs wen i crank the engine not wen the key is in the on position i thought that it should turn on and pressurize while in the on position

cruiser54

Because maybe the ballast resistor for your fuel pump, located on the driver's side inner fender is bad?

And maybe your CPS is weak? Have you tested it?

Have you done any of the things Flintstone and Mr Walker suggested?

stev-o

today i just took off my nss and cleaned it and reinstalled it and now i can move the shifter at all does anyone know why

DFlintstone

I've never had mine out, I did see this in that link though;

"The large nut doesn't require much torque. I made it just a bit tighter than hand-tight. Then I bent the locking tabs up to prevent the nut from coming loose"

Maybe that^? (You know, you can always click on "edit", if you ever want to go back and change spelling or add punctuation)

stev-o

ya i got mine only hand tight also and i gained my reverse lights back an it did start in park an nuetral

A grande ninja

I would def. check your cps. Ive had to replace mine 3 time in 2 years. Gotta love your renix. Its like an 8 dollar part and 30 min install maybe. Good Luck though.

DFlintstone

Great! So you got it? Yea, Grande, for around $40 at Napa you can get one that might last 12 years. (like my last one did).

cruiser54

Flintstone, I think you're on to sumpin'.

DFlintstone

lol. Guess most of us have the World Wide Web "at our fingertips". Others just have thumbs!