Greetings to all. I have a very well maintained 2000 TJ 4.0, Auto from the south. 132K miles. It starts and runs fine, no stumbling until "sudden death" in 4-15 minutes. It originally showed error codes for the crank position sensor, so that was replaced, along with the TP sensor since I know they fail. No more codes, same problem, Having access to a new ECM, that was changed. Swapped cam position sensor to no avail. Checked fuel pressure at rail--about 50psi, steady until after it dies. The only other clue I have is I caught the speedometer "pegging high" just as it quits recently. Still no error codes. My beloved TJ has failed me? Any guidance is greatly appreciated! Runs fine---until it doesn't! All stock drivetrain. Thanks!
Another "just quits running" mystery; 2000 TJ 4.0
- Thread starter T F Smoak
- Start date
Intermittent problems are absolutely the hardest to fix. Somebody will chime in here in a bit with some good suggestions but I wanted to say Welcome to the forum.
Greetings. Agreed---Made sure the crank sensor was Bosch since Mopar is rare now. I will restart quickly, usually, but ran only a short time once hot.
Upate---I swapped relays between the horn and fuel pump positions. I also put a coin under the idle stop on the intake manifold to raise the idle speed to 1000 rpm. It's been running with the AC on, 85F outside, hood up, for over 15 minutes now, but in gear really bogs it down. Plugs and wires have at least 45K miles on them now. I think that's my next move(?). Thanks! Still no codes.
Since you're experiencing the speedometer pegging high just before it dies, that could point towards an electrical or sensor-related problem, particularly with the instrument cluster or possibly the vehicle speed sensor (VSS).
Here are a few additional things worth checking:
Check for a Bad Grounds: Ensure that your grounds are clean and intact, especially around the engine and the ECU. A bad ground can lead to erratic behavior.
Inspect the Wiring Harness: Look for any frayed wires or connections that may be causing intermittent electrical issues. Pay special attention to any wiring that runs near the exhaust or other heat sources.
VSS Issue: Since you've noticed the speedometer acting up, it could be related to a failing vehicle speed sensor. Try replacing it if you haven't already.
Fuel Pump Relay: Sometimes, a failing fuel pump relay can cause the pump to stop working after a short period. Consider swapping it out or bypassing it temporarily to see if it resolves the issue.
Ignition System: Check your ignition system components, including the coil, distributor cap, and rotor, as these can lead to sudden drops in power if they fail.
ECU Issues: While you've replaced the ECU, it’s worth checking to see if there are any compatibility issues or if the new unit is functioning properly.
Test Your Fuel Pump: Although you mentioned fuel pressure is okay, it might be worth doing a "load test" to see if the pump is actually delivering proper flow under stress.
Look for Vacuum Leaks: Though less likely, a vacuum leak could cause issues with performance that might manifest under certain conditions.
Good luck, and let us know how it goes!
When it dies on you, is it normally while at idle, or will it die on you while driving with the engine under load?
It dies at idle. Thanks for the great advice. It's still going strong after 30+ minutes. Good thought on the speed sensor---Thanks!
If it does at idle try cleaning your idle air controller. There’s a thread here on cleaning that without removing it.
Thanks Greg. Will do. I'll be off line for awhile folks--Advise greatly appreciated!!
Get a can of carb cleaner and spray about a ⅓ of the can directly into the IAC slot on the throttle body while the engine is idling. Engine will want to die so you will need to feather the throttle while doing this to keep it running. If engine dies, restart it and continue.
Many thanks again to all. We're pretty sure it is the ground floating at the fuel pump/gas guage sensor as the indicator went to zero now. We'll report back later!
Any updates or solution? I am having similar issue with my 06 LJ - only happens under load or at idle. Dies while driving or idle, speedo pegs to over 100. Will restart okay, and then continue. This morning it happened after ~15 min drive while exiting a round-about. Died once, was able to restart and continue on road for next 5 minutes until I got to work. First did it last weekend in a drive through, then twice in the parking lot, and bucked twice on the road like it died for half a second and came back to life. Haven't driven it sense.
I do have Wranglerfix ECU as well as speedoDRD to correct the speedo because of the NP231 Teraflex extreme short shaft SYE changing the VSS sensor change to tone ring electronic speedo sensor (like the NP242).
I do have Wranglerfix ECU as well as speedoDRD to correct the speedo because of the NP231 Teraflex extreme short shaft SYE changing the VSS sensor change to tone ring electronic speedo sensor (like the NP242).
Your speedometer wiring and fuel pump wiring all run next to and over the transmission and transfer case on the way to the pump.
I'd deloom that section. My guess is you have wiring issues.
-Mac
I'd deloom that section. My guess is you have wiring issues.
-Mac
Greetings and sorry for the delay! It's fixed! We found a bad ground connection to the fuel pump. Guages Back to normal. Replaced the coil during an overall tune up. No more stalling. I think we nailed it finally.
Per my last post, our problems were resolved by fixing a loose ground at the fuel pump, and coil replacement during tuneup.
That’s fantastic, but @basic’s problem is what I was responding to.
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