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2000 Jeep Cherokee stalls after warm-up

This is just a random observation; I'm not actually working on the Jeep, yet. I have a small carpentry job about a mile and half from my house so I have been driving the Jeep too and from there without any problems. I have found that it is generally good to drive as long as you don't go too far. So, my thinking is that this is a heat related problem. Something under the hood is getting heat saturated and causing the Jeep to stall out. So, we have been experiencing bitter cold here in MD, 20 degrees and less. What I did was disconnect the heat sensor from the thermostat; this makes the elec. fan come on. I drove to my jobsite and even went up to the local hardware store for some things I needed. I drove back going about 5miles total. The outside temp was 19degrees. I parked in the driveway and let the Jeep run. For almost 2hours it idled without the temp sensor connected and the fan running full blast. I decided to reconnect the sensor and see what would happen. The engine temp was reading just below 210 degrees and the fan turned off. I shut the hood let it keep running and in less than 10minutes it stalled and couldn't be restarted. So my question is can the temp sensor cause the engine to cut out or is this just a symptom of another problem? What components under the hood and in direct line with the elec. fan can fail due to heat related issues? The fan blows right on the intake manifold and throttle body. Now all of the components have checked out when I tested them. The TPS is the only thing I have replaced and the original unit was only off voltage a very small amount and I probably could have left it alone. Anyone want to give me your thought on this? Thanks
 
Temp sensor would not likely do that, and it seems unlikely if the engine was running fine before, although it could theoretically go bad and make the engine run really rich. You can pull a plug and see if its soaked.

Sounds more like the CPS though
 
OK, so we're talking about heat soak issues here, even though it's very difficult to see how this could be a problem at 20 degrees F.

2000's only have one coolant temp sensor and your's read 210, so it's OK, but even if it read 260, it wouldn't shut the motor off.

The well known heat soak problem that the later model XK's (including our 2000's) do have is fuel vaporization in the injectors and fuel rail. Chrysler cheapened the design and eliminated the return line from the fuel rail to the gas tank that existed on earlier models. Mine hasn't been an issue, but I haven't been 4 wheelin in the summer yet. People add in circuits to make the efan run after it is shut off and at low speeds to minimize this heat soak issue.

Mine has a big silver heat shield between the manifolds and the injectors. Is it possible that yours is missing? If you add dry gas or use ethanol or possibly injector cleaning chemicals, it could lower the boiling point of the fuel.

Did you ever determine yet, if it's the spark or the gas that's missing when it won't run?
 
This is not the common heat soak issue for the following reasons:
1) The heat soak issue is only when you start your engine, not when it has already been running.
2) That silver heat shield has nothing to do with heat soak. It is part of the TSB to prevent garbage gathering in there and starting a fire
3) The TSB for the heat soak issue puts an insulator on the #3 injector.

Now that that is clear up.. about what is the engine temp when this happens? Did it just hit that temp, or has it been there a while.. perhaps it has something to do with the PCM switching from open to closed loop.
 
ehall said:
Temp sensor would not likely do that, and it seems unlikely if the engine was running fine before, although it could theoretically go bad and make the engine run really rich. You can pull a plug and see if its soaked.

Sounds more like the CPS though
Click to expand...

When you say CPS are speaking of the Cam or Crank Position Sensor? I've noticed CPS can be either of these sensors depending on who I'm talking with. CPS to me is Crank not Cam. Just looking for clarification. Thanks
 
Talyn said:
This is not the common heat soak issue for the following reasons:
1) The heat soak issue is only when you start your engine, not when it has already been running.
2) That silver heat shield has nothing to do with heat soak. It is part of the TSB to prevent garbage gathering in there and starting a fire
3) The TSB for the heat soak issue puts an insulator on the #3 injector.

Now that that is clear up.. about what is the engine temp when this happens? Did it just hit that temp, or has it been there a while.. perhaps it has something to do with the PCM switching from open to closed loop.
Click to expand...

Silver heat shield was on it when I purchased it and the dealership ran a service and recall report as part of the purchase.

The temp is just shy of 210 degrees. There is a hash mark then the number 210. The needle is about two needle widths past the hash mark. It is usually at this mark when it may or may not stall. At that point I'm on borrowed time, but no more than 30 to 40 minutes depending on the outside temp. The colder the outside temp the longer it could run. Right now it is flat out cold. I thought about the PCM loop swicthing and I guess that is possible. I will disconnect the elec. fan and the coolant sensor and see what happens.
 
winterbeater said:
Did you ever determine yet, if it's the spark or the gas that's missing when it won't run?
Click to expand...

Well, The fuel pressure is at 49-50psi all the way to stall. Thanks to the new fuelpump, and stays at pressure even after it stalls. Then over time it slowly reduces. I have sprayed starter fluid into the TB and it will sometime start but will not stay running, but on some occasions it will run and I will try to drive it, but only get a block or two before it stalls again. Then nothing will get it started until it sits for 30 to 45 minutes and cools down. Then it will start up and it is like everything is reset.
So, if I was to hazzard a guess I would say that not getting spark is the issue. Just a gues though.
 
I know you've been chasing this forever. What if the next time it quits running, you pull off the coil rail and put a spark plug in it and hold it to ground while someone cranks it. Because at this point you don't really know if the spark isn't there or if the injectors aren't firing.

Possibly one other thing to try would be when it stops running, disconnect the battery for 15 seconds and reconnect and try to restart.
 
I had the exact same issue with my 96 XJ (would crank but not start when hot, and would stall out when stopped). Then the CEL came on.

I disconected the battery for an hour to clear memory, and that fixed the problem. Have you had your battery disconnected for at least 30 minutes since all of these issues began? It is definately worth a shot.

Side note: This issue has occured twice since I have owned my Jeep, both times after I was tinkering under the hood and have disconnected/connected electrical connectors. I knew both times that I had not broken anything so I reset the ECU by removing power for an hour. This was a tip I learned from my autoshop teacher in High Scool. When all else fails, reboot!
 
gistecknician said:
I had the exact same issue with my 96 XJ (would crank but not start when hot, and would stall out when stopped). Then the CEL came on.

I disconected the battery for an hour to clear memory, and that fixed the problem. Have you had your battery disconnected for at least 30 minutes since all of these issues began? It is definately worth a shot.

Side note: This issue has occured twice since I have owned my Jeep, both times after I was tinkering under the hood and have disconnected/connected electrical connectors. I knew both times that I had not broken anything so I reset the ECU by removing power for an hour. This was a tip I learned from my autoshop teacher in High Scool. When all else fails, reboot!
Click to expand...

Thanks, I'll go one better for you. It is running with a new ECU. I did the power disconnect early on thinking that was it, but the problem was and is still there. Thanks for taking shot.
 
I guess the ECU reset was only a temp fix, startin acting up again today. Just checked my CEL codes and got 17 & 22, both related to the coolant temp sensor. What's weird is that I have a broken temp switch (broke recently when changing valve cover gasket) but I was under the impresion that the temp switch and coolant sensor were not related, I purchased a new temp switch and broke that one trying to install. I am going to have to pull the valve cover off to replace the temp switch with out braking it, I will let you know if this solves my issue.

The next time you get the Jeep to start, let it run for a while then check your temp gauge to see if it's working. Wonder if there is a connection?

Addition: check out http://www.naxja.org/forum/showthread.php?t=980561&highlight=coolant+sensor seems someone else here had a similar issue and got a code related to the Coolant Sensor, I may go ahead and relace this as well.
 
Last edited:
I actually checked the temp gauge with a multi-tester and it checked out. I heated some water to about 210 degrees, hooked it and it was less than 1000 ohms as it should be at operating temp.

Todays adventure involved getting it to kick up the P1391 on a regular basis. I have a reader and after it stalled today I went out and tried to get it too start. Of course it wouldn't, but it did kick up this code. I would erase it and start cranking the engine and sure enough it would kick it up again. Now the sad thing is, I have replaced both the CMP and the CKP. What could cause it to loose one or both of these signals and is it heat related? That's my question for the day!
 
winterbeater said:
So, if you pull the two bolts out and try pushing it down closer???????????? If it's not real close, you could file the holes open bigger.
Click to expand...
Wow! I'm not to sure I want to get into that. These are threaded holes and I wouldn't want to mess that up. I am going loosen up the bolts and see if there is any play in it at all. Then retorque everything to spec. If that doesn't work I'd like to take it out and compare it to a new one to see if the plate that the sensor is mounted to matches and as the sensor mounted in the same place. My thought is that it may be off just enough to be giving me all this grief after the engine warms up and everything get loose. All my problems started with this one little sensor and I did not install this sensor the last time, the shop did. This was the same shop that also started throwing parts at it when they couldn't figure out what was wrong. I'll keep you posted.
 
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