JessicatheJeep

Hello, I have a 1987 Jeep Cherokee Laredo inline 6 4.0 L, it will stall randomly and then wont start untill i wait about a day. I have to move into my new house in less than 2 weeks and i'm desperate.
Replaced:
Crankshaft Position sensor
Ignition Coil
Ignition Control Module
Distributor
Camshaft position sensor
spark plugs/wires

I'm completely at a loss. It still dies intermittently and I have no idea. I'm going to replace the fuel pump because that is my next best guess. but just in case, Could it possibly be the ECU? Any Ideas? Sorry about the novel, i just don't have much time. ANy help is much appreciated. Thanks

ThatAintStock00

When it stalls, does it stutter or just die like you turned it off? And does it try to fire back up or just turn over?

cruiser54

Do this just cuz. Your CPS signal and a bunch of other important signals run through it.
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, ECU, and some to the TCU, travel this path through the C101 connector.
The C101 connector 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 before bolting both halves back together.
　
Revised 07-17-2012

JessicatheJeep

When it dies, it's like i shut the engine off, it doesn't sputter. All of my power still works, but my speedometer and tachometer drop

JessicatheJeep

I'll give cleaning that a try. But also, when i try to start it it just cranks and cranks but it wont fire up

cruiser54

Do that first, then check your cPS output as follows:



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

timberwolf

could be fuel pump ballast resistor:



next time it stalls, jumper the wires together and see if it starts

ThatAintStock00

That didn't even cross my mind. you rock for that one.


With it just cutting out and you still have other functions and no engine, I am leaning toward the C101 connector as well now. Seems suspect.

JessicatheJeep

Thanks for replying guys. I'll try to clean out my c101 connector and see if it makes a difference