Jeep slowly died while driving and now it won't start

N4FunJeeps

New Member
Joined
May 24, 2020
Messages
4
Location
Tampa
1997 Jeep TJ 4.0 6Cyl
Looking for some advice
When driving Jeep began to slowly die

Wouldn’t fire after it died

15/20 min later started back up died after about 100 yards

Replaced Ignition coil

Distributor getting small spark

Jeep started ran at idle

Wouldn’t start back up again

Very slight spark to distributor now

Currently Will not start
 
First thing I would do is have the battery load tested (go to any auto part store and they'll do it for free). See what the test results are. Also, check the tightness of your battery terminals, and visually inspect them. What do they look like?

Also, is it throwing any codes?
 
First thing I would do is have the battery load tested (go to any auto part store and they'll do it for free). See what the test results are. Also, check the tightness of your battery terminals, and visually inspect them. What do they look like?

Also, is it throwing any codes?
The battery is only about a week old and terminals look good, no codes are being thrown.
Only idea that’s come to mind as what could be wrong is the crank position sensor
 
The battery is only about a week old and terminals look good, no codes are being thrown.
Only idea that’s come to mind as what could be wrong is the crank position sensor

Why would you think the crankshaft position sensor is bad?

Also, I'd still rule out the battery first. Just because it's a week old doesn't necessarily mean anything. Start with the simplest stuff.

When you turn the key, does the engine attempt to turn over, or does nothing happen at all?
 
Yes engine attempts to turn over, starter is brand new and strong as well
I’ll definitely get that battery tested just to rule it out as well
 
Also thinking the crankshaft sensor because if it doesn’t work it isn't sending a signal to the ECU at all, then the computer won't send any fuel to the injectors. Assuming the battery and everything is in working order since I was just able to bring a strong spark back to the distributor....
Seems like fuel isn’t getting to where it belongs and fuel pump is running well

appreciate all the ideas as well
 
Also thinking the crankshaft sensor because if it doesn’t work it isn't sending a signal to the ECU at all, then the computer won't send any fuel to the injectors. Assuming the battery and everything is in working order since I was just able to bring a strong spark back to the distributor....
Seems like fuel isn’t getting to where it belongs and fuel pump is running well

appreciate all the ideas as well

I have seen a CPS fail like you describe and I do not think it is unusual.
 
My 2000 did the same thing back in November. Replacing the crankshaft position sensor with a MOPAR replacement allowed it to start. I had also replaced the spark plugs right before it happened, so I replaced those again just to be safe...been fine since!
 
Check all ground cables. This could be as simple as not being able to get power to and from the coil. Also I've had crap coils brand new. And have had running coils crack and slowly seep oil until they overload. I always check the easiest parts first.
 
Since you said you have a weak spark, the battery is just about new and the starter is new I agree with Goatman.... I would check the voltage going to the coil. Bad coil or dirty connections could cause this problem.
Couldn't hurt to pop the distributor cap and have a look to see if there are any signs of problems inside.
 
I might have a similar issue. I took the Mrs. on a day trip (around 200 miles round trip), Jeep ran fine most of the way, but on our way home it was getting dark, and a tad colder with the top off so to avoid making my wife b*tch about being cold I jumped on the interstate I 70 from Richfield to Salina in Utah. Cruising along at around 80mph when the CEL came on, the Jeep sputtered a bit, but still ran ok. This light has been coming on for the last few months, most of the time giving me a code for a "small EVAP leak" so I have just been clearing it with my code reader. I pulled it into the garage thinking that I need to figure that evap leak out sometime so I can avoid having to clear the light all the time. A few days later I jump in the Jeep to run up-town and it wont start. I crank and crank, turning all fans/stereo, ect off so I can listen to make sure the fuel pump is working. I could hear it cycle, but it seemed to be really fast (maybe it always has been like this and its normal as I have never paid attention in the past). Anyways, being the type I am it couldnt wait until the next weekend when I would have time, so I pop the hood and start looking around, maybe a loose connection ect. I pulled the intake off of the throttle body, and crank, get a strong smell of fuel and boom, she fires up. I let it run for a bit, it did run a little rough, and then drive it around town mainly to charge the battery back up. The CEL comes back on and this time it gives me a code for CPS, as well as the EVAP leak. Long story short I have the CPS ordered from Amazon (Mopar brand) as well as a TPS (Mopar brand). Is there anything else I should do when I replace these? They should be here this weekend. I have read that it might be a good idea to clean the IAC, although I am not sure how to do it. I am fairly mechanically savvy, have replaced a clutch in my old cummins truck, clutchs in my buddies Jeep. Most of the stuff I have done has been on diesels, but hopefully the Jeep is fairly easy to work on as well. Any suggestions on additional items to check, clean, ect. would be greatly appreciated, thanks!
 
Mower2339,

IF the problem reoccurs where the engine will crank, but will not start and you are at home; IF you have a multi-meter there are three wires in the harness for the CPS. Ground, Signal to the PCM and Reference Voltage (5.0-5.2 VDC).
Check to see if you still have reference voltage. IF not.... then the problem may not be your CPS, but the Automatic Shutdown relay. The relay may be bad or dirty terminals on the relay.

To further troubleshoot you problem IF you believe the CPS is the problem; check out this troubleshooting video.

Troubleshoot your CPS
 
Mower2339,

IF the problem reoccurs where the engine will crank, but will not start and you are at home; IF you have a multi-meter there are three wires in the harness for the CPS. Ground, Signal to the PCM and Reference Voltage (5.0-5.2 VDC).
Check to see if you still have reference voltage. IF not.... then the problem may not be your CPS, but the Automatic Shutdown relay. The relay may be bad or dirty terminals on the relay.

To further troubleshoot you problem IF you believe the CPS is the problem; check out this troubleshooting video.

Troubleshoot your CPS


Thank You for the reply, I actually already ordered the CPS as well as a TPS as I figured the code that it keeps throwing is pointing in that direction. I guess if that does not fix it, then at least I will know that the CPS is a brand new factory Mopar CPS. I know that I need to clean the IAC, just not sure if that is an easy, or more difficult job. From what I gather online, it seems that it should be easy, ive just never done it before and have had experiences in the past on various vehicles where "easy" repairs/maintenance turn into nightmares lmao.
 
I just had the exact same problem.

Replaced the crank and camshaft position sensors - no more issues.

Jeep threw no codes.
 
When I had crank position sensor issues the first time the jeep would start fine if cold. But the minute it reached operating temperature it was was like the key got turned off only the steering wheel didn't lock. It wouldn't even crank until the engine cooled off. The second time, six years later, the same symptoms. So replaced it with an auto zone version ( I know I know ). The third time, two years later it would run till I shut it down. But then would crank but no start till it cooled off. Replaced the CPS again, I haven't had the no start issue. This time, I'm replacing it with a mopar sensor.
 
1997 Jeep TJ 4.0 6Cyl
Looking for some advice
When driving Jeep began to slowly die

Wouldn’t fire after it died

15/20 min later started back up died after about 100 yards

Replaced Ignition coil

Distributor getting small spark

Jeep started ran at idle

Wouldn’t start back up again

Very slight spark to distributor now

Currently Will not start
Did you ever fix the problem?
I think it sounds like the alternator.
Charge the battery over night and put it back in the Jeep. If the Jeep starts and you then can pull the negative side on the battery while the Jeep is running and it does then it's the Alternator. Then bring alternator to local Autozone or O'Reilly to have it checked out for free. They confirm it's broken.
If the alternator goes out and the Jeep would run for a couple miles until its dies.