Jeep engine shuts off randomly

Nachothemacho

Nachothemacho

New Member
Joined
May 17, 2019
Messages
5
Location
Texas
Hello new guy here. I own a 2000 Sport automatic with around 140k miles.
My jeep has been having a problem. When iam driving no matter the speed, my jeep loses all engine power and the RPMs drops to zero for maybe 1 second as soon as i let go of the pedal it goes back to normal. It doesnt stutter or jerk. It just randomly happens. It has done it at 30mph and 60mph.
This rarely happens, but its concerning. The longest time it has taken to recover is like 3 seconds. So its a quick rpm drop, pedal doesnt do anything, jeep starts slowing down then rpm jumps back up to how it was before.
It runs like a champ, it starts up with no problem, it idles perfectly. It has new spark plugs, clean air filter i cleaned the throttle body and replaced the Throttle position sensor hoping that would fix it.
I bought one of those 30$ code readers and its not showing up any codes.
It has also turned off while idling only once in my driveway. I was outside my jeep when it suddenly just stopped as if someone turned the key off, like i said no stuttering or anything.
Hopefully you guys can help me.
 
What is your fuel pressure? Along the injector rail you should see a schrader valve that you can put a gauge on.
 
  • Like
Reactions: TJ Jim
tworley said:
What is your fuel pressure? Along the injector rail you should see a schrader valve that you can put a gauge on.
Click to expand...
I have not checked that yet, but i wonder if running my jeep while it is low on gas can reproduce the sudden rpm loss.
In this past few days ive had been running on half a tank and ive noticed its doing it more frequently during my commutes, maybe just coincidence.
I will see if i can get a pressure gauge to check tho.
 
Could be a few things failing fuel pump, crank position sensor, there is a link to factory service manual Dre how to guides, and most folks prefer factory parts for the electrical stuff
 
It ended up being the Crank Position Sensor. I bought the oem part was like 95$. The old one was stuck hard to the housing unit. Pain in the arse, but eventually i got it out. Just posting incase other people have same problem. Thanks for the help and suggestion.
 
  • Like
Reactions: kmac5130, Huckster, KCsTJ and 2 others
Nachothemacho said:
Hello new guy here. I own a 2000 Sport automatic with around 140k miles.
My jeep has been having a problem. When iam driving no matter the speed, my jeep loses all engine power and the RPMs drops to zero for maybe 1 second as soon as i let go of the pedal it goes back to normal. It doesnt stutter or jerk. It just randomly happens. It has done it at 30mph and 60mph.
This rarely happens, but its concerning. The longest time it has taken to recover is like 3 seconds. So its a quick rpm drop, pedal doesnt do anything, jeep starts slowing down then rpm jumps back up to how it was before.
It runs like a champ, it starts up with no problem, it idles perfectly. It has new spark plugs, clean air filter i cleaned the throttle body and replaced the Throttle position sensor hoping that would fix it.
I bought one of those 30$ code readers and its not showing up any codes.
It has also turned off while idling only once in my driveway. I was outside my jeep when it suddenly just stopped as if someone turned the key off, like i said no stuttering or anything.
Hopefully you guys can help me.
Click to expand...

I know this is an old post….but my 06 4.0L six speed is doing almost, maybe exactly the same thing. Is there a way to test the crankshaft position sensor?
 
Huckster said:
I know this is an old post….but my 06 4.0L six speed is doing almost, maybe exactly the same thing. Is there a way to test the crankshaft position sensor?
Click to expand...

You can bench test it if you have enough alligator clips and a 5V supply. You can back probe one of the 5V sensor supply wires, but I did it with a phone charger. This video is for the cam position sensor, but they both work more or less the same way. You'll have to consult the FSM for your year to get the specific wiring.

 
Bleepin Jeep did one specifically for the crank position sensor, but you will still need to verify your wiring. Things changed on the 05/06 TJ. My video is for an 02, and Matt's is an XJ which is going to be wired similar to an earlier TJ.

 
hear said:
Bleepin Jeep did one specifically for the crank position sensor, but you will still need to verify your wiring. Things changed on the 05/06 TJ. My video is for an 02, and Matt's is an XJ which is going to be wired similar to an earlier TJ.

Click to expand...

Isn’t there a difference in color between the years that call for a bit of different pin outs? One is gray, one is black and they pin out different for the 5v, ground, and output signal?
 
TJ Jim said:
Isn’t there a difference in color between the years that call for a bit of different pin outs? One is gray, one is black and they pin out different for the 5v, ground, and output signal?
Click to expand...

There is definitely a variance across years. 97 is different, then 98-04 line up, then 05 & 06 change again. Check section 8W in the FSM for your year.
 
I don’t have a factory service manual. I did check for codes on the dash. Nada. So this hiccup in the electrical system has been going on intermittently for months. The engine dies for a second and then keeps running usually while I’m sitting at a traffic light. Although thinking about it, maybe under load it’s so fast I don’t even feel the engine hiccup. About a week ago the engine just died with all the dash light and electrics intact. Middle lane of a six lane stop and go Atlanta traffic. What a pain. TJ starts up 3 min later like nothing ever happened… just as blue lights came on behind me. The 4.0 runs fine most of the time although I did notice some rough running after a 3 hour drive a while back. Should I just put a crankshaft poison sensor on it? I’m not sure I have the electrical acumen to test this thing
 
Huckster said:
I don’t have a factory service manual. I did check for codes on the dash. Nada. So this hiccup in the electrical system has been going on intermittently for months. The engine dies for a second and then keeps running usually while I’m sitting at a traffic light. Although thinking about it, maybe under load it’s so fast I don’t even feel the engine hiccup. About a week ago the engine just died with all the dash light and electrics intact. Middle lane of a six lane stop and go Atlanta traffic. What a pain. TJ starts up 3 min later like nothing ever happened… just as blue lights came on behind me. The 4.0 runs fine most of the time although I did notice some rough running after a 3 hour drive a while back. Should I just put a crankshaft poison sensor on it? I’m not sure I have the electrical acumen to test this thing
Click to expand...

manuals are available for free here under the resources section ! Parts list too.....
 
  • Like
Reactions: TJTom and Huckster
I also read a post to which Chris responded about heat affecting the CKP and his advice to only get a mopar replacement. I have a Haynes manual that says to check the crankshaft position sensor, 1) disconnect the CKP electrical connector from the main wiring harness 2)connect an ohmmeter across terminals A and B (marked on the connector) The readings should be 200 plus or minus 75 ohms (engine at normal operating temp) 3) if readings are not to specification, replace CKP. I am not great with electrical stuff, but I’m going to attempt this today

image.jpg
 
@Huckster is that an actual printed FSM or is that from a Haynes or Chilton book? The font & column layout aren't right for the FSM but if it has good troubleshooting info I'm always interested.
 
1987 - 2011????

So one manual (that is smaller than our FSM) is supposed to cover the YJ, the TJ (and it's variations), and also the 3.8L JK?

That's cute. Tell me another one. ;)
 
  • Like
Reactions: macleanflood
hear said:
1987 - 2011????

So one manual (that is smaller than our FSM) is supposed to cover the YJ, the TJ (and it's variations), and also the 3.8L JK?

That's cute. Tell me another one. ;)
Click to expand...

See…you’re too young to understand the importance of a good Haynes manual. My first engine rebuild was completely done from a Haynes. 100,000 miles later that engine was still running great. There was no internet or you tube to become a master mechanic. 😂
 
  • Like
Reactions: Huckster
TJ Jim said:
See…you’re too young to understand the importance of a good Haynes manual. My first engine rebuild was completely done from a Haynes. 100,000 miles later that engine was still running great. There was no internet or you tube to become a master mechanic. 😂
Click to expand...

I've got a nice touch tone cordless phone I bought for my dorm in 1993. I mean, as long as we're talking about things that used to be useful.
 
  • Love
Reactions: TJ Jim
I am almost 65 years old. Not extremely tech savvy. I like the Haynes and Chilton manuals. YouTube is great fun to watch. The Haynes manual had the ohm test for the crankcase position sensor. I recently had surgery and it’s hard to get under or in the engine bay…very irritating but I’m working on it
 
Top Bottom
Back