530turbo

I have been messing with cherokees for too long and now my new project is acting funny! It starts totally fine when cold or sitting but if i go drive for even 5 min and turn it off wait 5 min then it will just turn over and over and sometimes it smells flooded, which makes no sense i changed the filter, distributor air filter and plugs. i have a feeling it could be the crank pos. sensor or the throttle pos. sensor but i have no idea because it has some symptons but not all. cause when it starts it runs fine. it seems like the idle is a lil high but it runs fine. i unplugged the tps while it was running and it made it stumble so i think it might be fine. and also sometime it will kinda jerk when i let of the gas while driving? so i just want to know what anyone might think before i go throwing money away

so here is symptons. cold starts and runs fine, when turned off it just keeps cranking over and smells flooded somewhat. to get it to start sometimes i just have to put my foot to the floor while turning it over, once started it kinda stumbles for a sec then runs fine, kinda idles high, and kinda jerky when driving and let off gas?

possibilities? cps? tps? fuel could be dripping in from fuel pressure regulator after turned off?
hopefully someone could help me!!!!

tjwalker

1. First, what year and engine? Critical information so we can provide the most accurate replies.

2. Have you seen a check engine light? Even if the answer is no, I generally recommend checking to see if you have any "pending" or "stored" codes that can yield clues. Codes are absolutely invaluable in troubleshooting.

3. As far as engine management sensors go, three things come to mind. Throttle position sensor, coolant temp sensor, and camshaft position sensor. If the engine NEVER kills or stalls while driving it and is ONLY symptomatic if you turn off a hot engine, (please verify this) I don't think this is a crank sensor issue; that is not the way they fail. The cam sensor can fail that way as if they suffer thermal (heat) failure, it simply uses the last cam sensor signal to allow the engine to continue to run. But once you turn the engine off, it has to start with a fresh signal and that is where trouble comes in. However, if you changed the ENTIRE distributor, then you do have a different cam sensor in there......

Both the cam sensor and the throttle position sensor can be tested. Coolant sensor can be tested, but kind of a PITA; most guys just replace them; located on the thermostat housing.

If you let us know what year your XJ is, I can send you information on testing your throttle position sensor.

Tx9h6e4cuda

What area of the world are you in?
Did the symptoms start when there was a change in the weather? From cool to warm?
I had the same problem with my 01 Cherokee it turned out to be fuel boiling in the fuel injectors. I changed the fuel I run to non oxygenated fuel until I do my injector upgrade. When I do the upgrade I will be wrapping the fuel rail and injectors with heat deflecting tape.

cruiser54

REALLY need the year/engine etc before proceeding as the systems vary throughout the years. Please fill out your profile and/or include this info in your post.

530turbo

oh sorry for not saying the year it is a 1991 cherokee 4.0l h.o. and there was no check engine light but there was a couple codes stored when i checked by ignition turning on, off, on, off, on and it showed a manifold air temp sensor, Map sensor, Coolant temp sensor (which i think is because it has a aftermarket temp gauge and it has a mechanical sensor instead of factory which whoever did it left the old sensor plugged in and taped off to the side) but i just checked for the faults today and that is what i found!! so i am kind of thinking it might be the MAT sensor because i unplugged it while it was running and it didnt change anything and it didnt have to much of a reading with my volt/ohm meter.
but let me know what your ideas are!! thanks!

530turbo

oh sorry for not saying the year it is a 1991 cherokee 4.0l h.o. and there was no check engine light but there was a couple codes stored when i checked by ignition turning on, off, on, off, on and it showed a manifold air temp sensor, Map sensor, Coolant temp sensor (which i think is because it has a aftermarket temp gauge and it has a mechanical sensor instead of factory which whoever did it left the old sensor plugged in and taped off to the side) but i just checked for the faults today and that is what i found!! so i am kind of thinking it might be the MAT sensor because i unplugged it while it was running and it didnt change anything and it didnt have to much of a reading with my volt/ohm meter.
but let me know what your ideas are!! thanks!

and i also tested the Throttle position sensor and i had a steady climb while testing and opening the throttle while the key was on but engine off so i think if i remember that is what i should be looking for??

tjwalker

Here is a link to testing many things on the 87-90 XJ. Suggest it as a bookmark.

http://www.lunghd.com/Tech_Articles/...iagnostics.htm

Andre139

Hi

I had the same problem with my 99 xj 4 litre where it would start perfectly when cold and if you switch it off after its warmed up it just wont fire back up. So I replaced the ignition coil, all plug leads, fuel pump and Crank position sensor. But no luck. Still would not start. So my last option was to change the Cam sensor. So i did. Problem solved. Havnt had any problem since. Spent a lot of money on all the new Mopar parts but now it will run for another 180 000 miles with no hickups as before. Hope this could be of help to anyone.