My TJ won't start

9

99TJ_Firefighter

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May 17, 2024
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North Dakota
Hello Everyone,
I'm new to the Forum but came here looking for help. I have a 1999 Jeep Wrangler Sport with the 4.0L and automatic transmission. I've had it almost 3 years now and absolutely love it...... When it runs... I recently changed the torque converter in it and after the install I took it for a test drive and I made it a 1/2 mile and it stalled and now won't start. It turns over but will not fire. I'm getting fuel, and have a spark but it's looks to be a week spark. After reading many threads I changed out the Crankshaft Position Sensor but that didn't solve the issue. Unfortunately I did order it from Amazon and have read those are junk. I also replaced the spark plugs and plug wires but not sure where to go from here. When I try to start it and let off the key it seems to want to backfire as well. The tach doesn't move when I turn it over either. Any help would be GREATLY appreciated cuz I'm to the point I want to push it into the river..
Thanks in advance everyone!
 
First, welcome to the best automotive forum on the Internet! Second, the TJ Resources forum on here has many official Jeep documents available for download, including the Factory Service Manuals (FSM) for all model years of the TJ. Third, you don't mention any Diagnostic Trouble Codes (DTC) or a Check Engine Light (CEL). If there are codes present, or the CEL is on, sharing those codes is helpful. If there are no codes, that information is helpful, too. You said you changed the Crankshaft Position Sensor - why? Normally, a DTC would be associated with a problem with that sensor. Did you have a DTC?

Since this occurred during the first drive after reinstalling the torque converter, and since I'm a skeptic when it comes to "coincidences" in the automotive diagnostic world, the first thing I'd look for is a connector that is either fully or slightly unplugged. It's probable that, during reinstallation, a connector was put together, but not locked, and when you drove, it came apart. Also, look for a pinched wiring harness, or a wiring harness routed incorrectly (like very close to the exhaust). Again, it's possible that there wasn't a short or break in the harness initially, but as you drove, it occured.

Good Luck!
 
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Thanks for the input. The CEL isn't on and I'm hoping to get a code reader tonight. I replaced the censor because I read alot of forums and watch many videos and it was a common solution to the problem. I will double check all of the connections to make sure nothing came loose. Thanks again!!
 
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99TJ_Firefighter said:
...because I read alot of forums and watch many videos...
Click to expand...
I bought my TJ about the same time you bought yours. If you stick around here, I think you'll find, like I did, that this place is several levels above the common Internet automotive forums in terms of helping a TJ owner. There are some very, very helpful, and very, very experienced members here...
 
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If you changed the torque converter then you pulled the transmission and the starter.

You might have missed reconnecting some grounds. You might have some loose bolts.

I'd get your battery on a charger and double check everything you touched.

Cam position sensor is also right in there.

-Mac
 
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macleanflood said:
If you changed the torque converter then you pulled the transmission and the starter.

You might have missed reconnecting some grounds. You might have some loose bolts.

I'd get your battery on a charger and double check everything you touched.

Cam position sensor is also right in there.

-Mac
Click to expand...

100%, the torque converter is not the issue here. If it turns over then it's not the neutral safety (which would've been my first guess here). Although pulling the transmission shouldn't involve touching any grounds. I would definitely double check everything at the starter & crank position sensor, since you had to remove both of those. I've never had it happen, but I've heard that the CPS can be sensitive to alignment, so check that it's in there good & square.

Also, everybody focuses on the crank sensor, but the cam sensor performs an almost identical function and both need to work for the jeep to start. I would look at the wiring around all the sensor pigtails, they have a tendency to get exposed & twist/short, and seem to have a way of doing so right after you've done an unrelated repair.
 
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