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New CPS Needed w/'87-90 Harness Upgrade?

I just replaced the CPS in my wife's 1989 after doing Search and Research here.
Now it starts up and runs for a short time (under 5 minutes) and just shuts off.
Somewhere in my search I found a a reference to "Chrysler service bulletin 18-51-88" (Google it to find the PDF). The Cherokee has the upgrade already installed.

The bulletin says, in part;
Source: Chrysler service bulletin 18-51-88
The symptoms described above could be caused by a weak signal from the CKP sensor. A new CKP sensor and harness is available to correct this problem. The new CKP sensor is available in a kit, part number 83100066. The kit includes the new CKP sensor, and a sensor patch harness for connecting the new sensor directly to the engine control module (ECM).
AND
7. Locate the old CKP sensor on the bellhousing. Remove the CKP sensor lead from the retaining clip. Remove the CKP sensor retaining bolts, and discard the CKP sensor.

Is this a different CPS sensor than the one I just bought at NAPA or am I having some other problems?

After the replacement I cleaned all the under hood connectors, battery conections and ground wires.

Thanks!
 
Still won't keep running!

Got back from dinner, reached in the window, turned the key and started right it up.

No problems, well maybe a bit of rough idle at first, idles fine as it warms up.

5 ~10 minutes later, it just stops . . .
It won't start back up when warm.

Ideas?

Wrong CPS? Dirty flywheel? Bad karma?
What else acts like a failing CPS?
 
do a fuel pressure test.Maybe your pump is failing....or another thing to think about is you might have dirt in the bottom of your tank that clogs up the fuel pump and then when you shut it off the sediment drops back into the bottom of the tank.HTH
 
600dollarxj said:
It wouldnt be the crank position sensor, that is only used to start the car. (Or that's what I was under the impression of anyway)

No, the CPS is definitely integral in keeping the engine running. Often, a hot CPS will kill the engine.

One trick to try when the engine dies is to put water or ice down near the CPS to cool it off.

Mike...are you going to the Christmas party later today? All the great Jeep minds will be there.
 
After it dies and won't start again check for spark at the plugs. If there is strong spark it's not the ckp. Check for fuel problems. I have bought aftermarket parts that didn't work correctly. This is like a $25 part at the dealership, or maybe that was the tps.... can't remember, but that could be your problem as well. If the ckp didn't fix the problem then maybe you should start checking other sensors, ground wires, etc.
 
xjohnnyc said:
. . Often, a hot CPS will kill the engine.

One trick to try when the engine dies is to put water or ice down near the CPS to cool it off.

I never would have thought to cool the CPS / CKS down.

Fired it up, let it run a few minutes while I read my Chiltons until it shut down. Tried to restart, nothing.
Checked the resistance and no reading (should be 125 ~ 275 Ohms).
Got out the long funnel for a better aim and added water to cool the CPS down, the reading came up to 230 Ohms.
Fired it up . . ran . . died . .
Again, fired it up . . ADDED a little stream fo WATER . . it kept running, until I stopped.
Did it several times for entertainment. (Sorry I couldn't make to the chapter party, I'm sure I'll read about it.)

So the New CPS is defective and needs to go back to NAPA?
The Old CPS reads 235 Ohms sitting here, I'll pop it in the toaster oven and see if its' resistance goes away with heat.

Any other ideas?
Do I need to get out the 4 foot extension again to replace the new CPS?

Slo-Sho,
I jumped the "white ceramic block". Thanks for the tip, but it didn't help.

Others,
I replaced the plugs and cleaned the ground wires, connections and contacts after I swapped the CPS.
 
wim hoppenbrouwers said:
:wave1: Hallo. What about the ignition coil? It can fail when hot!
greetings
And greetings back from Southern California!

True, but pouring water on the CPS for cooling kept it working. Water on the coil is not a good idea.

I put the original "failed" CPS in the oven to see how it would react to 200 F ( 100 C ) heating. Its' resistance went from 235 Ohms to 375 Ohms and spiked higher (700+) when I pinched the wires with my fingers.

It may "sound" like I know electronics, I DON'T. If anyone knows what a CPS should read, please let me know.
OR;
Am I on the wrong track with our stalling Cherokee?
Thanks again
 
PhotographerMike said:
If anyone knows what a CPS should read, please let me know.

I'm looking at the Renix fuel injection pdf manual, and it says the CPS shoud read 200ohm +/- 75.

...and it sounds to me like you are on the right track. Replace that CPS.

By the way, I've melted the CPS wires on the exhaust manifold before. If you end up with one which has a real long lead wire, make sure you tie it up, or route it in such a way that it won't melt (or come into contact with the exhaust).
 
As dumb as this sounds, go to the dealership and buy the factory crank position sensor and replace the NAPA one you have in there. I'm not sure what goes on with these after market sensors, but on the the recommendation of a mechanic friend of mine I did this. My 2000 XJ has been running great ever since. I replaced the crank sensor 2-times before going to the dealership for the part. Search my post and avoid the nightmare I endured over this $100.00 part!!!
 
As dumb as this sounds, go to the dealership and buy the factory crank position sensor and replace the NAPA one you have in there. I replaced the crank sensor 2-times before going to the dealership for the part.
Second time was a charm for me at NAPA, the first one was defective per the "oven test" done back in December 2007. Been running fine since I last posted to this thread over a year ago.

I will agree that the dealer is the best / only place for some parts (search my "Engine Squeal" thread for Harmonic Balancer problems).
There are a couple of dealers that do online sales at a nice discount from "list price" instead of adding 20 ~ 30% over list.

Mike
 
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