1998 Jeep Cherokee Jeep goes off while driving

Tiny
ROADRUNNER00777
  • MEMBER
  • 1998 JEEP CHEROKEE
  • 4 CYL
  • 2WD
  • AUTOMATIC
  • 124,124 MILES
My 1998 Grand Cherokee Jeep Laredo goes off while I'm driving in the highway but it starts right back up and now it goes on for 2 minutes and just dies I put a new camshaft sensor and coil and distributor cap, rotor and spark plugs and wires. And it just doesn't start at all now.
it cranks with power but won't start.I try jerking the computer but no help.
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Monday, July 12th, 2010 AT 4:02 PM

14 Replies

Tiny
BLACKOP555
  • EXPERT
Try not to be jerking or hitting on the computer we dont wanna harm anything.

What I would like you to do is use a spark tester and make sure it is grounded out to the engine good on a nice clean ground spot. Then check for spark on all cylinders. Not just a few do all of them. Is the spark a bright blue spark that fires rhytmically with all the other plugs? Any odd ones? If spark is good move on to fuel pressure. You can push schrader valve on fuel rail and if fuel comes out you know your getting fuel but you do not know the pressure or volume.
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Tuesday, July 13th, 2010 AT 6:13 PM
Tiny
ROADRUNNER00777
  • MEMBER
Hi, I been working all day on my jeep since reading your reply I went out and bought me a spark tester first I study it on line to learn how to use it.I learn how to do minor things on my cars from reading books and practicing on my own cars. Tune ups to changing brakes pad. So this stuff I'm doing now is new to me.
I put the spark plug wire on the tester end and ground the clip, I had my wife crank the engine there was no spark then I try it on the coil wire no sparks. But I ask my neighbor if I can try it on his car and still no spark so I think the tester is damage good I be taking it back tomorrow. Now the funny thing is I also bought a fuel pressure gauge and learn how to use it reading on his site they show it on a video when I put the gauge on the port valve then turn key on the pressure went to 42 or 44 around there. My jeep says the pressure should be 44.2 to 54.2.
So I wanted to see if it drops or I bled it first and turn the car on to see if its the regulator. The books says it should drop to 5. But if it don't have a vacumn hose the reading will stay the same.I don't know if I read that right but anyway when I turn the key to crank the ignition the jeep went on so I turn it off took the pressure gauge off and started it again the jeep went on with no problem I let it idle for ten minutes and it just went off. It started again but I turn it off and check my relay fuse with a tester it was good but went I went to start the jeep it wouldn't start at all.I first I thought it was the PCM but I don't think is that.I can't figure this out.>?
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Wednesday, July 14th, 2010 AT 9:20 PM
Tiny
BLACKOP555
  • EXPERT
Keep guage on you can run the vehicle with that. If you keep turning key on and off does pressure get any higher or stay around 44?

They mean the pressure will raise 5 higher without vaccum line on it because the vaccum will not pull open the valve in regulator causing pressure to drop you need a vaccum guage to simulate this with vehicle off or run the vehicle.

If you want you can take a spark plug and rig a ground strap on that and try to see if it will spark did you make sure where you were grounding it had no paint underneith? Try right on the starter if it will go that far. Or a good clean metal spot on radiator or a bolt that goes into the engine block.

Whats fuel pressure now that jeep died on you and wont start? Try bangign on the tank to see if youc an get pump to spin faster. Anything? When engine fires up check the fuel pressure and keep an eye on it. And when it finally dies if it does see if pressure drop caused it to die out or what.

As soon as you replaced cam sensor did vehicle stop starting?
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Thursday, July 15th, 2010 AT 2:24 PM
Tiny
ROADRUNNER00777
  • MEMBER
Hi, Today I put the pressure gauge on before starting it. The fuel pump is working because I open the gas top and ask wife to turn key just to on and I can hear the pump for about 2 seconds. But we want to know what pressure it has. Ok with the jeep off and only on on position it read 44 I then started it to see if it goes on sure enough it crank on strong for like 12 minutes this time I left the gauge on and it had a steady number never got lower I snap the throttle to see if anything changes and it just went in between 44 to 50 stood flashing around there, I bang on the gas tank nothing change now I kept an eye on it to see if when it goes off does the pressure drop and since it didn't I said let me try the air condition on to see what happens well when I put the air condition on the jeep went right off but the pressure never change. Then I try starting it and it wouldn't start, it had a strong crank but won't start.
Then I got a new spark tester but I don't see any spark when I put on the wire and I ground it on a bolt that has no paint then I took the wire from the coil and try it and no spark I thought maybe I don't know how to use it so I put the my light tester that I own and put it in the wire boot and ground it to the negative battery side and crank it and no spark.

Yesterday it went off for no reason today it went off as soon as I put on the AC?

When I put the cam sensor it work fine for about a week before starting to go off on me when driving. First I put the new coil when it started stalling then I was told once the coil goes bad the cam sensor is next so when the jeep started stalling on me again I put a new cam sensor but it still the same?
I took a picture of the jeep with the gauge on so you can see it but can't find the wire to transfer to the PC.
Thanks.
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Thursday, July 15th, 2010 AT 8:24 PM
Tiny
BLACKOP555
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So im having trouble here help me out. Is the vehicle running. And if so for how long. You said it wasnt starting in orginal one. Now it wont start but is showing fuel pressure. But you say your cracking the throttle and seeing a change. Only should be doing that with vehicle running. Just please clarify
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Thursday, July 15th, 2010 AT 11:02 PM
Tiny
ROADRUNNER00777
  • MEMBER
So im having trouble here help me out. Is the vehicle running. And if so for how long. You said it wasnt starting in orginal one.

Sorry for the confusion. Yes at times the Vehicle starts and running and there is times it won't for days but when it does only for 12 minutes tops. It doesn't start once it goes off well at least last night it didn't. The other night it started 3 times after going off, but then it didn't want to start again. The weird thing is sometimes it starts sometimes it don.T but if it does start not for long.

"now it wont start but is showing fuel pressure. But you say your cracking the throttle and seeing a change. Only should be doing that with vehicle running. Just please clarify "

yes it is showing fuel pressure with vehicle only on on position but not running. Then I ask wife to crank it to see if it starts up. Sure enough it happens to go on so that's when I snap the throttle. It ran for about 12 minutes under garage and I said let see what happens if I just turn on lights or AC soon as I turn the AC on it shut right off. The reading on pressure stood the same. Now the other night it stood on for only 10 minutes without me putting anything on like the AC or Lights. Just shut off. I just happen to run downstairs and start the jeep to see if it went on before sending this reply and no it won't start. Weird ain't it. Desperate need of Vehicle need to go food shopping soon. Thanks for your help.
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Friday, July 16th, 2010 AT 8:15 AM
Tiny
ROADRUNNER00777
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Hi, I bought a new spark tester and try it about an hour ago 7:30pm. First I try to see it the jeep start and won't start this time so I took out a few spark plug wire and try them on the spark tester one at a time there's no spark. At all.
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Friday, July 16th, 2010 AT 7:24 PM
Tiny
BLACKOP555
  • EXPERT
Since you have NO spark and vehicle isnt starting I woudl assume its ignition related. Would be nice if you could see if you have spark when it will start but you sound like you really need the vehicle so well really have to just start trying things.

First off do you have a test light or a noid light? If so take the igntion coil connector and check for 12v on one side with key on other side should have 0v.

With test lead hooked up on positive and clip on negative side. Crank engine test light or noid light shoudl be flashing. Signaling igniiton pulse.
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Monday, July 19th, 2010 AT 1:57 AM
Tiny
ROADRUNNER00777
  • MEMBER
Finally the electricty is back on in my house bad storm hit us.

"test lead hooked up on positive and clip on negative side. Crank engine test light or noid light shoudl be flashing. Signaling igniiton pulse".

I have a test light and did exactly as you instructed but when I crank the engine no flashing. The only time I saw the test light flash was when I put key on position only the light when on for 2 seconds and never lit up again unless I turn key on position with no cranking?
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Friday, July 23rd, 2010 AT 7:38 PM
Tiny
BLACKOP555
  • EXPERT
So light just sat the uniluminated with you cranking. Not good.

Next thign to do is check if you have +12v on the one side all time. Key on, engine cranking. Anytime but with key off. If thats good and the noid light isnt flashing or isnt illumiating all the time then you have a issue with the ignition control module side of the vehicle. Be it wires ffrom module to coil or the module itself

*edit* also crank and cam sensors too forgot to mention that if your getting no pulse
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Sunday, July 25th, 2010 AT 8:33 AM
Tiny
ROADRUNNER00777
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No pulse or light, no +12 volt. No pulse from crank sensor and cam sensor neither but the cam sensor is the only one that's new.
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Monday, August 2nd, 2010 AT 1:01 PM
Tiny
BLACKOP555
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Where are you checking for pulsing on the cam and crank sensor. Right on the sensor with the connector unhooked is best. When cam and crank is probed one lead on each of the connectors turn multimeter to ac volts setting and crank engine. Shoudl get a refrence.

Do you have a rpm reading on interior dash?

Check your ASD aka auto shut down relay in the fuse box make sure thats working.

Try running a wire going to coil for +12v on the coil + side
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Wednesday, August 4th, 2010 AT 9:56 PM
Tiny
ROADRUNNER00777
  • MEMBER
I just decided to go out and buy a crank sensor it cost me about 63 bucks and sure enough that was the problem. It started up right away. Drove 41 miles and it hasn't shut off. That's what it was all along, glad it was not the computer. Thanks for your help.
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Thursday, August 5th, 2010 AT 10:59 AM
Tiny
BLACKOP555
  • EXPERT
Glad to hear you have problem fixed.

Just odd the crank was acting that way. Especially without throwing codes or a issue with NO BUS written on the display
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Thursday, August 5th, 2010 AT 1:15 PM

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