cherokee re start issue..

[humpy]

my lil bro has an 01 cherokee sport 4.0 auto trans...120k on it...it runs good but when you shut it off and leave it sit for more than 5 mins it cranks and cranks and cranks then finally starts and runs rough for bout 30 seconds smelling like its flooded then cleans up and runs good...did a full tune up on it including a new coil and still no fix...check fuel pressure when turn key on and its right at 49 pounds...and here is the kicker...when its under 30 degrees outside temp the problem goes away...:mad: :mad: any ideas?? leaky injector?? how the hell do ya test that if so?? any help would be AWESOME!! thanks in advance!!!

[Flxratd]

poss tw sensor or i had a fuel pressure reg go bad on my 95(not sure if the same setup) but it would dump fuel like crazy.

[bgwyllys61]

could be something as simple as heat soak in the injectors, the engine bay gets extremely hot, and can sometimes cause issues with getting the injectors so hot that they wont function properly, or could be the pressure regulator, or a number of things, I know this doesnt help much, but its a start

[Coppertop]

Could be a TPS (Thottle Postion Sensor) while the engine is cranking,push the acel pedal down to see if it starts any quicker.

Nick

[jfiscus]

visiy/search naxja.org for more help.

[Flxratd]

did you find the solution or light it on fire ?

[Haddix505]

Its a Jeep. Just light it. Lol

[humpy]

na my little brother is still trying to figure it out...its his... im trying to help him fix it because he moves downtown next month for main campus school and i dont want him having car clifton if you know what i mean....we replaced the tw sensor like you said and it made no changes...its weird man i havent seen anything like this....i almost wanna say it has a leaky injector or 2 and when it sits its dumpin fuel down in the chamber and basically flooding itself... is this possible?? how would you diagnose???

[jfiscus]

http://www.naxja.org/forum/showthread.php?t=1015751&highlight=restart+sitting

Sounds like the pump or pressure regulator, etc is not holding pressure in this thread.

[itbrokeagain]

Naxja is very helpful

[Redriverranger]

It does sound like a leaky injector, or the ect sensor is telling the computer it is cold all the time, effectively choking it. Were you checking the fuel pressure while you were having the issue? Or, it is not firing while you are trying to start it, and then finally when it does, it is flooded. Good luck. That really narrows it down.... :D

[humpy]

figured it out....somethin about a heat soak in the #3 cylinder...common problem prior to 01 4.0 jeep engine....i guess the exhaust heats up the injector itself and ruins the injector...dealer sells a $10 shield to fix the problem...i think were gonna replace the injector and re seal them all and install the shield...and then...i get to do my bro in laws 2000 cherokee cause it has the same fn problem!!! thanks for all the input and hope our troubles may help someone else in the future...

[humps823]

Hey, I'm the little brother in question. I let this go for a while, and have replaced everything above. I had a check engine light back a few months ago and had the codes run- it was a misfire cylinder #3: fuel issue. I did a little reading on this and apparently there ws some big heat soak issue that ruins the #3 injector. I have just recently replaced the #3 injector. It runs much smoother, but it still cranks forever. I had an exhaust leak before the 2nd O2 sensor, so I replaced the whole exhaust (converter had been cut on, so i replaced it as well). I am seriously stumped. I still think it is either choking or flooding itself, as I smell fuel in the exhaust at startup, and fuel mileage has decreased significantly. Before this issue started I could easily get 18.5-19.5 highway, and on a recent all speed limit trip to Michigan I barely broke 17.

I had been checking the fuel pressure while cranking. When I first turn the key I have ~46-52psi and it stays between there while cranking and running.

My next step will probably be to replace the Idle Air Control and clean out that area. This is only a hunch, and I don't think it'll work, because the high idle works at startup and my idle is pretty steady once it is up to temperature. I had read how to see if it is working once, I pulled it out and turned the key and it went in and out and adjusted itself, so I really don't believe it is the IAC, but I'm running out of options. It has stalled on me about 5 times, but only when sitting at a stoplight with it in Drive.

Any additional suggestions would be much appreciated!

Thanks

[Black00XJ]

I had thesame problem. Mine ended up being the temp. my motor would "over heat" after shut down and w/o enough time to cool, it would run in "limp" mode. I added a $30 thermostatic fan controler and $5 low temp thermostat and havent had this happen again... that was 6 years ago and she stills runs cool.

[Black00XJ]

Also, I wired my elec fan to run regardless of ignition being on or off. In the summer when its the hottest the fan will kick on about 5 times after shut down. I have never had a problem with a low battery either... Hope this helps. Ive know a few other guys with 00 & 01 XJ's that do this. They dont have enough air flow. My buddy fixed his by adding a cowl hood and the problem went away... I didnt have $550 plus shipping so I cheaped out lol.

[itbrokeagain]

I had been checking the fuel pressure while cranking. When I first turn the key I have ~46-52psi and it stays between there while cranking and running.




Fuel pressure seems a little high. I believe 40 is the number you want. I know that is what a 4.0 Yj needs.

[8UP]

The o-rings on the injectors were known to leak on the 4.0's. Look for fuel around the injectors.

[humps823]

The o-rings on the injectors were known to leak on the 4.0's. Look for fuel around the injectors.

Also, I wired my elec fan to run regardless of ignition being on or off. In the summer when its the hottest the fan will kick on about 5 times after shut down. I have never had a problem with a low battery either... Hope this helps. Ive know a few other guys with 00 & 01 XJ's that do this. They dont have enough air flow. My buddy fixed his by adding a cowl hood and the problem went away... I didnt have $550 plus shipping so I cheaped out lol.

I put a 180 stat in and it doesn't seem to be running much lower... I could kick myself for not running the 160 now, but I was afraid it would make it want to dump more fuel to bring temperature up. I'm gonna throw one in to see what it does, as I'm still running around 190-195 moving, and close to 200 idling. radiator has been thoroughly flushed several times and the mechanical fan is good. I also wired in that thermostatic controller, and it seems to kick on around 170. Wired it straight to battery, and it cycles 3-4 times after shutoff. also no problems with battery, as i actually was sittin listening to stereo for 4 hours after it did its cycles and it still cranked well.

I also replaced all injector o-rings when I replaced the #3 injector. There didn't seem to be any leaks before or after this.

[humps823]

Fuel pressure seems a little high. I believe 40 is the number you want. I know that is what a 4.0 Yj needs.

What regulates the pressure on these? I'm afraid you're going to tell me it's in the tank... I'm getting to know my jeep better and better every week, even more than I'd like to, ha!

[humps823]

One thing I forgot to mention... Someone had tried to cut my cats out last fall, but I guess someone spooked them and they left the job unfinished (half-asses). I crap-welded it back together in a hurry, but they had cut before the 2nd O2 sensor, and it leaked a little. Now I've put in a new cat and exhaust, but is it possible the computer calculated for the leak and never reverted to what it should be? It's a long shot but I wanted to make sure I mentioned that.

[humps823]

It does sound like a leaky injector, or the ect sensor is telling the computer it is cold all the time, effectively choking it. Were you checking the fuel pressure while you were having the issue? Or, it is not firing while you are trying to start it, and then finally when it does, it is flooded. Good luck. That really narrows it down.... :D
whoops, didn't see this one. yep, I was checking the fuel pressure and it read between 46-52 pounds, which another member said might be too high.

I put a coil on it as well, so I'm hoping it's not an issue with firing. It runs fine after it runs about 30 seconds, but it seems to be drinking a little extra fuel.

What is the ect sensor and where is it? How does one test that sensor?

thanks!

[humps823]

I got it! I found a listing of what the coolant temp and ambient temp resistance readings are supposed to be, and since i'd already replaced the coolant temp sensor (with no change), I did a reading on the ambient air (or air charge, or MAT, there were several names for it), and got a reading of 5k ohm at 92 degrees. It should have read ~2200 ohm (colder temps yield higher resistances) I calculated this, and a couple other tests, to be off (low) by about 32-37 degrees F, depending on the temperature. Bought a new one at advance (P# WT2000) for $23.49, and she starts right up now!

The info for the resistance readings came from here (http://www.lunghd.com/Tech_Articles/Engine/Basic_Sensors_Diagnostics.htm)

Hopefully this info saves somebody else a lot of time and money! Test $25 sensors and replace before buyin $100 coils and $50 injectors haha.