Cranks, no spark, no start, CPS test?

mhead · May 6, 2005

My 92 XJ I-6 Autotran ran great this afternoon but won't start now. Engine is cold, it cranks, I can hear the fuel pump, there's fuel pressure at the rail, checked the fuses and disconnected/connected the CPS connector, coil connector, and distributer connector but it still won't start.

Is there a ohm-meter test I can do on the CPS or some way to tell if it is any good? Any other suggestions?

(if you see a similar post by me it's because I clicked 'submit new thread' and got an error message. As of right now I can't see the post so I guess it went into the ether...)

Thanks!
Mike

DPC · May 6, 2005

9 out of 10 times it is the CPS that causes this. I am sure there is an ohm test for it just do a search and you should find it here. How many miles on the CPS thats in there now?

mhead · May 6, 2005

CPS and whole vehicle has 197K. Young by Jeep standards...?

DPC · May 6, 2005

My moneys on the CPS. It is overdue by milage anyways. The Jeep with live long but the electronics wont.

Runnin'OnEmpty · May 6, 2005

Mike, backprobe between the middle CPS connector and ground; resistance should be less than 5 ohms. (I use straight pins to stick into the connectors; this saves the wiring and insulation. Then take the readings off the pins.)

Then backprobe between the middle terminal and either of the end terminals. Verify that one of the end terminals has a 5v signal present. Then backprobe between the connector that didn't have the 5v, and the middle terminal. With the engine cranking, the meter should read a voltage alternating between 0 and 5v.

(If you have an averaging voltmeter, it'll read about 2.5v.)

Hope this helps, and good luck......

mhead · May 6, 2005

Thanks for the test suggestions. I figured with 197K it was time for the CPS working or not so I just replaced it. I've heard the job was hard but it isn't really. It must be done from underneath the vehicle. I disconnected the front drive shaft and laid it aside. There was a cable to the trans that I unhooked and laid aside. After this I could relatively easily reach the two CPS bolts with a double extension and a swivel. Only maybe 15 min to get it out. Put back wasn't so bad. I could get one hand up there to place the bolt and start the threads.

But still no spark. This is my only car so I gave in and had Auto Club tow my Jeep to the dealer. They will troubleshoot it for $87. Ok, I've seen a lot of horror stories on this site about dealers and it goes without saying that my fingers are crossed at this point. Maybe I'll have something good to report in a couple of days. Stay tuned...

Mike

ChuckD · May 7, 2005

mhead said:
Thanks for the test suggestions. I figured with 197K it was time for the CPS working or not so I just replaced it. I've heard the job was hard but it isn't really. It must be done from underneath the vehicle. I disconnected the front drive shaft and laid it aside. There was a cable to the trans that I unhooked and laid aside. After this I could relatively easily reach the two CPS bolts with a double extension and a swivel. Only maybe 15 min to get it out. Put back wasn't so bad. I could get one hand up there to place the bolt and start the threads.

But still no spark. This is my only car so I gave in and had Auto Club tow my Jeep to the dealer. They will troubleshoot it for $87. Ok, I've seen a lot of horror stories on this site about dealers and it goes without saying that my fingers are crossed at this point. Maybe I'll have something good to report in a couple of days. Stay tuned...

Mike

New CPS, I would say coil. If not coil then maybe the connection to the coil.

JEONLYEP · May 7, 2005

mhead said:
But still no spark.
Mike

Mine is the same story as Mhead (Mike) How would one test the coil to see if it's bad?

I figured that almost 200,000 (73,000 since I bought it) that the CPS was needed. so it's new, but still no spark.

PS I also put rotor and dis cap, since I've never changed them in the 73K that I've owned it.

TIA

Daryl

Runnin'OnEmpty · May 8, 2005

Daryl, to test the coil, connect an ohmmeter between the positive and negative terminals (the ones connected to the wiring harness). The resistance should be about .95 ohms to 1.2 ohms at room temperature.

Then connect the ohmmeter between the positive coil terminal and the high voltage tower (where the coil wire attaches). The resistance should be about 11K ohms to 15K ohms. Good luck.

mhead · May 10, 2005

The story continues... So I didn't have the time to do more than swap the CPS. But I should have since now I'm embarrased to report that the dealer determined it was the coil, swapped another on, and she's running again just like always. Pep boys sells the coil for $40 and it's in stock. Looks like a 10 minute job (my coil is mounted on the passenger side of the motor). Dealer charged me $249 (^**^%%##)!

Oh well, now it's working.

So the lesson here is be agressive. Don't just buy the CPS. Buy the coil also. Would'a saved a bundle plus the time to have it towed and recover it.

Thanks for the advice. Guess I should'a taken it before I gave up. It's my only car and I needed it....

MudslinginXJ · May 10, 2005

Glad you got it figured out. I had to replace both on mine and it worked out for me. I wont ever take my jeep to a dealer, best bet for me is to fix it on my own. Thats one reason why im glad i found this site.

Cranks, no spark, no start, CPS test?

mhead

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DPC

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mhead

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mhead

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