runs/dies/runs/dies/runs--get the picture.

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  #1  
Old 02-22-02, 09:14 PM
jeep87
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Question runs/dies/runs/dies/runs--get the picture.

My 87 jeep cherokee laredo is having a problem. It likes to run a while and then out of the blue it will die. Sometimes it will start right up other times I have to wait 20 minutes or even longer before it decides to start again. Conclusion so far is that it is losing juice to the ignition coil(ignition control module). Where is the best place to start looking to fix the problem. Please help!!

6 cylinder fuel injected 4 wheel drive 4 door
 

Last edited by jeep87; 02-22-02 at 09:29 PM.
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  #2  
Old 02-22-02, 09:43 PM
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You have no spark when it dies? I have had to replace the coil /module on one of these 4.0's because of a no-spark condition. Sounds like it has a small break in a wire in the coil and when it heats up, the wire expands to interrupt the circuit. After it cools, and the windings contract, the circuit is completed again and will work until it heats up again, etc...

Make sure your coil connections are clean and tight first, have the coil checked before you buy a new one.
 
  #3  
Old 02-23-02, 12:00 PM
jeep87
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where to go to check the coil??Local mechanic/dealer/ or who???
 
  #4  
Old 02-23-02, 01:49 PM
mooser1
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your local auto parts store may be able to check the coil for you........if you're handy with an ommeter you can check it yourself...

Connect an ohmmeter between the positive (+) and negative (-) terminals (the terminals which are connected to the engine wiring harness) on the coil.
To test the secondary resistance, connect an ohmmeter between the positive (+) coil terminal and the high voltage cable terminal on the coil, then measure the resistance between the positive (+) coil terminal and the coil case; the resistance for the case should exhibit infinite resistance.
For coils manufactured by Diamond, the primary resistance at 70-80F (21-27C) should be 0.97-1.18 ohms and the secondary resistance should be 11,300-15,300 ohms.
Coils built by the Toyodenso company should exhibit a primary resistance at 70-80F (21-27C) of 0.95-1.20 ohms and a secondary resistance of 11,300-13,300 ohms.
Replace any coil with a new one if it does not meet the specifications.
 
  #5  
Old 02-23-02, 05:39 PM
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If I remember correctly, it's not that simple on this vehicle. I think the coil has the electronic control module built in, with a connector with several wires. Might be wrong though.
 
  #6  
Old 02-23-02, 08:31 PM
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if you are losing spark most of the time it is due to a bad crank position sensor the old amc modules rarely ever went bad. on the 4.0 and 2.5 fuel injected engines
 
  #7  
Old 02-23-02, 09:20 PM
danc37166
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I AGREE WITH BEJAY
 
  #8  
Old 02-24-02, 06:03 AM
jeep87
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updated problems

Okay here's an update all. By the way thanks for all the tips. Saturday I got brave and decided I would drive it to my place of employment to have it there to work on im my free time. Anyway I got it about 10 miles then it died. sat around 15 minutes and it started right up. It made it about 3 miles then died again. Waited another 15 minutes, started up again. Did this about every mile or so after that. Anyway, here's how it acted and what I did. On one occassion during the process when it started to die I worked the accellerator and it would stay running a while longer before dying. On another occassion I exchanged the coil with a used replacement coil I had picked up at a salvage yard. One time it worked the next it wouldn't. On the coil there is an electrical connector. I connected power to it and it started. Once again one time it worked the next it didn't. Anyway I finally got it to my destination. Here's my conclusion after the trip. It's almost got to be something before the ignition coil, a sensor or something. But also it seemed like maybe it was the fuel pump dying out, are there wires connected somehow?? Crankshaft position Sensor tell me more about that please. I thank you all for your input and hope to hear from you soon. Please Help.
 
  #9  
Old 02-24-02, 06:10 AM
Joe_F
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Some electronic components as they heat up will quit when they are faulty.

Ford had a problem with the TFI module doing just that, and there is a class action issue against them on it.

Look in the links in my signature file and use that as a guide to test some of the parts in question.

Vapor lock will also cause issues of dying when hot as well.
 
  #10  
Old 02-24-02, 05:58 PM
jeep87
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is there any way to bypass the wiring to the coil if it is a sensor?
maybe send a hot wire directly to the coil to see try to narrow down where the problem is??
 
  #11  
Old 02-24-02, 06:08 PM
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Are you sure you don't have spark when it dies? You need to know this before we can go further. There are a lot of things it could be. Find out if you're losing spark, or if you're losing fuel. Then we can start tracking it down.
 
  #12  
Old 02-24-02, 06:53 PM
Gix
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im pretty sure this vehicle has that combination module and coil assembly as mentioned in an earlier post how ever if you have already swapped this assembly with a used one on hand and problem didnt solve itself , i would be looking at the crank sensor , usually located way in the back of the engine compartment bolted to the bell housing
 
  #13  
Old 02-24-02, 06:54 PM
jeep87
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i will check more this week but before when it died it had no spark whatsoever at the distributor or the coil. but after yesterday's little ordeal i am not sure of anything with it except that it is a piece of junk. Not really,if I could just fix this problem, which is probably something i am overlooking, it would be a reliable source of transportation.


once again thanks for your input.
 
  #14  
Old 02-24-02, 08:12 PM
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The crank sensor, as mentioned, would be a good place to lay the blame if you have no spark, and tried a known-to-be-good coil/module. It should be on the driver side at the top of the bell housing, just behind the engine. It is easily accesible and held on with 2 10mm bolts to the best of my recollection.
 
  #15  
Old 02-24-02, 09:17 PM
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This sure sounds like a fuel pump to me. Before I went any further I would make sure that the pump is not vapor locking or failing. Check that first, is it hot to the touch, is it pumping,etc?
Also did u get fuel before this started, any weather changes in your area. Remember, KISS, start with the easiest.
I dont expect you to recall Joe F but this sounds similar to my 626 problem!
 
  #16  
Old 02-25-02, 03:41 AM
Joe_F
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How could I forget ?

It could be a fuel problem. That's why he's been given good advice here on how to track it down .
 
  #17  
Old 02-25-02, 05:37 PM
jeep87
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ok here's the latest

was reading the manual--good thing to do huh. was reading on the camshaft position sensor located inside the distributor. Decided to take out distributor to get a good look at it. When i got distributor out i noticed that it had some play(up and down) in it. So I read on and found the distributor diagram. Seems that it was missing a spacer gasket/o-ring that must have broken or something. So I got one but unfortunately got sidetracked and didn't get it put together. Should get it together tomorrow and give her a test run.
My theory is that the distributor was vibrating up and down and causing the sensor to give a bad reading to the computer and shutting itself down.

Agree or disagree.

Let me know.

thanks again
 
  #18  
Old 02-25-02, 07:48 PM
Joe_F
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Missing parts cannot be a good thing

Check it out and let us know what you find.
 
  #19  
Old 02-25-02, 10:33 PM
tstokka
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get a true blue service manual and look up the no-start conditions and follow the tree. that will lead you to your faults.
 
  #20  
Old 03-11-02, 04:16 PM
jeep87
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no spark/short somewhere

ok here's what's up.

put spacer in distributor, replaced pickup coil in distributor.
needed done but still not the problem of losing spark.

pulled off negative cable and it died. shouldn't the alternator keep it running?? with neg. cable off i took test light and ran it from the post to the frame and it lit up like a christmas tree. was told it wasn't supposed to do that. Now i got the good fortune of locating the short. any ideas where to start?? has this happened to anyone before??

Please help!!!!!!!!!
 
  #21  
Old 03-11-02, 06:05 PM
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The light will illuminate that way if you have anything on in the vehicle. If the key was on, a door open, if you have a under-the-hood light. Make sure nothing is on. If your battery hasn't been draining over a period of time, you likely don't have a short. If the light still comes on with everything off or disconnected, pull one fuse at a time out of the fuse block until you find the one that turns the light off. That will be your culprit circuit.
 
  #22  
Old 03-11-02, 07:42 PM
Joe_F
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Pulling the cable off while the vehicle is running is a sure fire way to wipe out the diodes in the alternator. The alternator output should be checked only with a digital meter, nothing else!
 
  #23  
Old 03-11-02, 07:52 PM
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Interesting problem. I skimmed through...Are you sure you don't have fire (spark) when it's dying. It sure sounds like a fuel filter or fuel pump problem to me! I would start looking in the direction of the fuel filter (cheapest) first.
Good Luck...I'm gonna watch this one.
 
  #24  
Old 03-11-02, 08:27 PM
jeep87
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dirty dan

not fuel filter--changed it
could fuel pump be killing spark??it's pumping fuel when it's not starting. something is shutting down and causing no spark.
 
  #25  
Old 03-12-02, 03:50 AM
Joe_F
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What does your service manual say?

You do have one after all this trouble, right ???

Check the link in my signature file for some ideas, if not, purchase a service manual/subscription and go from there.

Changing parts won't get you there .
 
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