Crank but no start on my 99 TJ

One other symptom I want to throw out there. I've noticed since I bought this Jeep that the ignition seems strange. Shortly after buying the Jeep I inserted the wrong key into the ignition and started it and the engine started but issued extremely rough. Once I realized what I did and inserted the correct key, it fires right up and ran normally.

Also, when the key is in the ignition and the ignition is switched on, the key can still be slid in and out of the ignition. I've never experienced an issue like this where the ignition would accept and start with an incorrect key.

Not sure if this is possibly related to this crank no start issue I'm battling.
 
Lots of us have the removable key feature, I don't think it's a likely factor. It's interesting that it will start with the wrong key but runs rough. The ignition tumbler is a known failure point and isn't too hard to replace so I might have that on my todo list anyway given that it seems to be a little wonky.

I've never done one ounce of reading on it, but do you happen to know if your jeep is SKIM equipped? I'm only mentioning it in the hopes that somebody who knows more than me about it will be able to say if it is or isn't a possibility.
 
hear said:
I've never done one ounce of reading on it, but do you happen to know if your jeep is SKIM equipped? I'm only mentioning it in the hopes that somebody who knows more than me about it will be able to say if it is or isn't a possibility.
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Good question and I'm not sure if I have a skim equipped model. I'll have to research that further unless someone more knowledgeable can tell me how I can confirm that.
 
GregBelleville said:
Good question and I'm not sure if I have a skim equipped model. I'll have to research that further unless someone more knowledgeable can tell me how I can confirm that.
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A gray ignition key contains a code chip inside which indicates the TJ has the SKIM system, a black ignition key indicates there's no SKIM system.
 
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Jerry Bransford said:
A gray ignition key contains a code chip inside which indicates the TJ has the SKIM system, a black ignition key indicates there's no SKIM system.
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Thanks Jerry! So it appears I do have a SKIM required TJ then. In your opinion do you think there's any correlation with the ignition tumbler accepting an incorrect key(and starting) with this crank no start issue?
 
GregBelleville said:
Thanks Jerry! So it appears I do have a SKIM required TJ then. In your opinion do you think there's any correlation with the ignition tumbler accepting an incorrect key(and starting) with this crank no start issue?
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The SKIM system won't prevent the engine from starting but it'll kill the engine in a couple seconds if the key doesn't have the correct chip in it. When that happens it will also illuminate the amber SKIM symbol on the instrument cluster which is the outline of a key with a line through it.
 
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So posting an update with a little more info on the pattern I'm seeing with the Jeep to see if it sheds any light on possible causes.

I've only been able to tinker with the Jeep on weekends, so it sits idle for several days at a time. So far, the Jeep will start just fine after sitting for several days. If I let the Jeep sit at idle, it will do so for about 10 minutes or so and then it will inevitably stall. Once it stalls on me, it will not restart, it just cranks endlessly, but doesn't fire back up unless I let it sit again for several days. It seems like the stall doesn't occur until the engine warms up?

Is this a clue to anyone as to possible source of my problem? Help! Wanna get my baby running again!
 
Although probably not your current problem, but I would check all your grounds and clean them up and ensure they are solid. The one circled for sure.

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GregBelleville said:
I'll have to check to confirm that, I'm not 100% sure, but I don't believe they do.
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have you cleaned the throttle body? MAP Sensor? IAC Valve? Good air filter? Those can all affect idle.
 
What about checking fuel pressure? My 97 has a Schrader valve on the rail...newer models got rid of it... would be nice to know what the pressure is through starts and no start situations.

-Mac
 
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macleanflood said:
What about checking fuel pressure? My 97 has a Schrader valve on the rail...newer models got rid of it... would be nice to know what the pressure is through starts and no start situations.

-Mac
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Got a loaner pressure gauge this morning. Fuel pressure is right around 49 psi and holds steady. The fuel pump was replaced about 2 months ago.
 
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GregBelleville said:
Jerry when you say you're suspicious of the circuit are you referring to the sensor itself?

So the tach should rise while the motor cranks?
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Yes the tach should rise when cranking the engine and obviously anything in the crankshaft position sensor circuit including the sensor, connectors, wiring, etc. could cause a problem for it. So no, not just the sensor... anything in its circuit which includes the PCM. The CPS drives the PCM which derives the engine rpms from it and then drives the tach. Likely the sensor but....
 
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