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Discussion Starter · #1 ·
I've got an 02' WJ with the 4.7 (Non H.O.) that has ran fine until a few days ago. The car would start and die after going down to idle RPMs (maybe 1000 or a little more). Now it doesn't start at all, only cranks. Fuel pump is good but doesn't kick on most of the time. I'd lean towards it being a bad PCM but the check engine light stays illuminated. Security light turns off. Wiggling PCM wires doesn't seem to help. Have checked fuses, doesn't seem like any blown. Does anyone have any tips? Could it possibly be a bad crankshaft positioning sensor or IAC?

Thanks in advance
 

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engine cranks, CEL is on, security light on?

use a scanner get codes - post ALL codes. At least try the key on off trick.
Post fuel pressure PSI. - If not able to we can work around.
Use other key - advise about light. The codes may help determine why light is on.
when engine is cranking are the injectors pulsing? My thinking is the CKP signal is missing
 
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Discussion Starter · #4 · (Edited)
engine cranks, CEL is on, security light on?

use a scanner get codes - post ALL codes. At least try the key on off trick.
Post fuel pressure PSI. - If not able to we can work around.
Use other key - advise about light. The codes may help determine why light is on.
when engine is cranking are the injectors pulsing? My thinking is the CKP signal is missing
No codes stored. Check engine light only on the "on" position. I can try to post fuel pressure but seems like fuel pump not working most of the time? Also unfortunately I don't have another key LOL. Key shouldn't be the problem anyways though because the security light turns off on the "on" position. I'll go out and try to start it here in a bit.

Thanks for the help everyone. I'll let y'all know if anything changes!

Edit: went out to start it this morning. Charged the battery overnight. Started and ran fine for maybe 2 minutes. Battery voltage while running 13.7ish. Could that be a problem? Also, not saying this could be anything, but when it died the temperature was just starting to rise, just over 100. Saw on a different post that a bad battery might cause this problem but I don't know. Might get the battery tested today or tomorrow at Walmart so we'll see!
 

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No codes stored. Check engine light only on the "on" position. I can try to post fuel pressure but seems like fuel pump not working most of the time? Also unfortunately I don't have another key LOL. Key shouldn't be the problem anyways though because the security light turns off on the "on" position. I'll go out and try to start it here in a bit.

Thanks for the help everyone. I'll let y'all know if anything changes!

Edit: went out to start it this morning. Charged the battery overnight. Started and ran fine for maybe 2 minutes. Battery voltage while running 13.7ish. Could that be a problem? Also, not saying this could be anything, but when it died the temperature was just starting to rise, just over 100. Saw on a different post that a bad battery might cause this problem but I don't know. Might get the battery tested today or tomorrow at Walmart so we'll see!
Battery voltage should be more than 14
measured with a multimeter / voltmeter.
Forget the guessing gauge on the dash.

Have you tried it Easy Start / ether yet?
If so, what happened please?
 

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Discussion Starter · #6 ·
Battery voltage should be more than 14
measured with a multimeter / voltmeter.
Forget the guessing gauge on the dash.

Have you tried it Easy Start / ether yet?
If so, what happened please?
Yeah battery voltage is around 13.7 with mulitimeter. Swapped in a new battery (June) from a TJ and still had the same problem. Haven't tried ES or ether because the fuel pump works but it seems like it isn't staying on..? It may or may not be the problem but I went ahead and bought a CKP sensor this morning. Probably won't do it today but maybe tomorrow morning I'll install it. 🤷‍♂️🤷‍♂️
 

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remember the fuel pump will only have 12v for @ 2 seconds if jeep does not start.
The key here would be to check if the injectors are pulsing when cranking engine, that would give us an idea if CKP signal is generated and seen by PCM.

My 2¢ a CKP should be considered a routine maintenance item. SO dont feel its a hopeless attempt to correct.

Advise after replacing sensnr OR checking inj pulsing.
 

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Yeah battery voltage is around 13.7 with mulitimeter. Swapped in a new battery (June) from a TJ and still had the same problem. Haven't tried ES or ether because the fuel pump works but it seems like it isn't staying on..? It may or may not be the problem but I went ahead and bought a CKP sensor this morning. Probably won't do it today but maybe tomorrow morning I'll install it. 🤷‍♂️🤷‍♂️
If it doesn't fire with Easy Start, you have a spark problem.

If it fires & runs a bit with Easy Start, you have a fuel problem.
 

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Discussion Starter · #9 ·
remember the fuel pump will only have 12v for @ 2 seconds if jeep does not start.
The key here would be to check if the injectors are pulsing when cranking engine, that would give us an idea if CKP signal is generated and seen by PCM.

My 2¢ a CKP should be considered a routine maintenance item. SO dont feel its a hopeless attempt to correct.

Advise after replacing sensnr OR checking inj pulsing.
I've been trying to remove the old CKP sensor this afternoon but it won't budge. It will turn and wiggle but it doesn't want to come out? Is there any trick to removing it? Again, thank you for all the help. I think I'm narrowing down!
 
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