Won't start when it warms up?

Ok, my xj runs and drives fine. When I'm just in traffic the temperature rises to about just over 210 (middle; not hot) while regular driving is around 190ish. Now while the temp gauge is in the middle, if I turn it off, it will NOT start back up until its down to about 200. So I have to wait 15 or so mins to let it cool down. What could this be? Thanks

When this happens, it still cranks strong, it just wont start. I've changed the ignition coil with no luck.

edit: I have a 98 6 cylinder

That has CPS written all over it, happened to me. Does it ever cut out and die on you? You could try dumping some cold water on the sensor and see if that helps, if it does, replace it. BTW the CPS is on the top of the bellhousing on the drivers side.

88 Wagonman said:

That has CPS written all over it, happened to me. Does it ever cut out and die on you? You could try dumping some cold water on the sensor and see if that helps, if it does, replace it. BTW the CPS is on the top of the bellhousing on the drivers side.

Click to expand...

Yea I was thinking that or the TPS, which was a problem in another xj i have... It died out on me once, usually it's just that it won't start back up if it gets warm. I'm going to try that tomm. How much do they usually cost BTW?

abc20abc said:

Yea I was thinking that or the TPS, which was a problem in another xj i have... It died out on me once, usually it's just that it won't start back up if it gets warm. I'm going to try that tomm. How much do they usually cost BTW?

Click to expand...

I have never seen a tps cause a no start on an XJ, in fact when I was having high idle problems I would actually unplug it and start the engine. I bought my last CPS for under 50 bucks I think. Try the cold water thing and clean the connector. Another thing to look for is if the wires for it are on the exhaust pipe.

Hi,
If you do fit a new CPS and it is the No1 suspect, make sure to zip tie the CPS cable well away from the exhaust, you don't want it melting through anytime soon!

88 Wagonman said:

I have never seen a tps cause a no start on an XJ, in fact when I was having high idle problems I would actually unplug it and start the engine. I bought my last CPS for under 50 bucks I think. Try the cold water thing and clean the connector. Another thing to look for is if the wires for it are on the exhaust pipe.

Click to expand...

Sometimes my 90 won't start and if I unplug the TPS (engine side) she will fire right up. But that's on a cold engine.

Sounds like a CPS...just went through this on a friend's 88 this weekend. It started off as dieing in the middle of the road, and would crank back up after a few minutes of cooling off....then it got to where it wouldnt start at all unless it was completely cold (had no spark or fuel if you tried).

New CPS and it's back on the road good as new.

Ok, so I got a new CPS (fucking cost me $93, but hey it was the only place that had it in stock) So, I found it on the truck, but it looks like a hell of a spot to get at? no?

Jesus $93???? We paid about $35 from Advance this past Saturday!

Yes, it's in a real tight spot...drivers side of the transmission, right up on the backside of the bellhousing at about the 1-2 o'clock position if you're standing facing the front of the Jeep. Universals and long extensions are definitely your friend on this job. If your Jeep is lifted it does make it a lot easier to get to.

The two bolts holding it on are 7/16" in size if I remember correctly. Since we didn't have the right type of universal, we got away with a really long extension and got at it from underneath the Jeep.

Edit: The one I was working on was a 88, and I see that you have a 98. Not sure if the newer ones have this or not as i've never done it to mine, but the 88 had a plastic piece with foam on the bottom that the sensor sat in, and the plastic piece sat on top of the bellhousing (it's used to keep dirt and other crud out of there)......20 year old plastic was extremely brittle and snapped the minute we tried to put it back on....so just a FYI if yours has it as well, which I don't see why it wouldn't unless they came up with a better design over the years.

UNCC_99XJ said:

Jesus $93???? We paid about $35 from Advance this past Saturday!

Yes, it's in a real tight spot...drivers side of the transmission, right up on the backside of the bellhousing at about the 1-2 o'clock position if you're standing facing the front of the Jeep. Universals and long extensions are definitely your friend on this job. If your Jeep is lifted it does make it a lot easier to get to.

The two bolts holding it on are 7/16" in size if I remember correctly. Since we didn't have the right type of universal, we got away with a really long extension and got at it from underneath the Jeep.

Edit: The one I was working on was a 88, and I see that you have a 98. Not sure if the newer ones have this or not as i've never done it to mine, but the 88 had a plastic piece with foam on the bottom that the sensor sat in, and the plastic piece sat on top of the bellhousing (it's used to keep dirt and other crud out of there)......20 year old plastic was extremely brittle and snapped the minute we tried to put it back on....so just a FYI if yours has it as well, which I don't see why it wouldn't unless they came up with a better design over the years.

Click to expand...

Thanks for the info man. I got mine from Advance Auto too!! lol

Here, I wrote a write-up on how I did it if this will help anyone in the future:
I put it in a half hour ago.... took me an hour and 20 mins. I used a 1/4'' ratchet, 3'' extension, and 7/16'' socket on both bolts. They werent super tight so i was able to loosen it with that ratchet. My truck has a 3'' lift so that probably made it easier. I did both of the bolts from under the truck. At first I tried a universal but it was easier without it. After a while of turning with the ratchet (you only have enough through for a click or two) I was able to take them out with my fingers after a little. I then unlpugged the old one and plugged in the new one (plugged it in before I bolted it on) It wasn't that bad, I have skinny arms so that probably helped too. Also I cable tied (like someone told me here) the wires away from the exhaust mani. Also, I have a 5-speed, I don't know if that makes a diff with the space you have to work with compared to an auto...

I actually didn't test it out yet (well I started it, but I didn't get it hot). So tomm I'll come back with the test results. Thanks to everyone here who helped me.


Edit: Yes it has the plastic but it didn't break or anything.for me.

Well good to hear your problem should be fixed now.

Out of curiosity, how many miles are on your Jeep? The one I worked on last week had around 170K....just curious to know at what mileage yours failed.

And yes, having skinny arms definitely does help on this job....my big hands and fairly big arms didn't help...lol.

UNCC_99XJ said:

Well good to hear your problem should be fixed now.

Out of curiosity, how many miles are on your Jeep? The one I worked on last week had around 170K....just curious to know at what mileage yours failed.

And yes, having skinny arms definitely does help on this job....my big hands and fairly big arms didn't help...lol.

Click to expand...

You're not going to believe me but... 169, 5xx

abc20abc said:

You're not going to believe me but... 169, 5xx

Click to expand...

Well that's cool...about the same mileage then.

Ok, so I installed it yesterday and drove it all day today and it is perfect. Not only did it fix the problem but it even starts faster than usual.

I just wanted to say that the old CPS was FILTHY. Crud was layered and layered on the actual sensor area. I believe that it only needed a cleaning but I put a new one in anyways.

The one we pulled out last weekend was fairly dirty too, but not so much on the actual sensor part....more on the outside from one of several oil leaks on the Jeep.

Glad to hear your problem is solved!