Howdy CF! I've spent a fair amount of time googling this and haven't come up with anything that seems to fit my problem

I've got a 96 OBD1 XJ that after 10-20 minutes of highway driving on a hot day, will indicate 210-220 or a bit more. On cool days this isn't much of a problem.

Already replaced the radiator (unrelated problem over the winter), fan clutch, last year I did the CPS and a few other things.

However, the annoying side effect of this is, if I go on a quick jaunt 20 minutes away, turn the car off for a few minutes, and then try and start it back up, it will crank but not start, after 5 minutes or so it will cool off enough, where it will start, but run rough, sputtering and having no power. I've been able to keep it running and after I'm up to 35mph or so, it normals out and everything is okay (or just wait longer and it will cool down). However, if I do the same drive but turn the car off, and start it right back up immediately, it will work seemignly just fine.

A friend has notice the fuseblock gets pretty hot, and thinks the relays may be too hot, in the past I've changed those(specifically the fuel pump relay) out for spares in the glove box with some success, but might just be a placebo.


Does anyone have any suggestions on this? Thanks

 

When it's hot and won't start, check right away for spark. If none, suspect the coil and/or CPS.
If you have spark, next I'd check fuel pressure.
Do you smell any gas, like an injector leak?

 

the heatsoak will cause the injectors to not work properly and cause it to run rough. mine does that sometimes, but it always starts. check to see if youre condensor is blocked up not allowing good airflow to the radiator.

what does you're coolant look like?

 

Do CPS's go bad that quick? I haven't had a chance to test spark yet, but no smelling gas.

Condenser is pretty buggy, any tips to clean that out without major disassembly?

Coolant is good.

 

Ya-know....I seem to be hearing lately about allot of Jeeps screwing up after being parked hot, and the news it telling me the country is having a heat wave.

Then there are these "TSB'S" (Technical Service Bulletins), from Jeep about protecting the injectors from heat. (boils the fuel)

Idk if they mention if that would be aggravated by the check valve, regulator or injectors letting the pressure drop faster than it normally would. Anyway, I think the TSP calls for heat shielding or insulation or something...

96.??? I don't know.....

 

There have been a lot of overheating and/or won't start hot threads lately, lol. You could probably calculate a outdoor temp Vs. number of overheat + no-start threads conversion factor and predict the weather.

 

I spray mine with a garden hose and let the bugs soak for a few minutes. Then blast the hose from behind through the radiator to flush them out.

 

Ha! Yea. No kidding. Watching here for about a year, funny how lots of things seem to come in groups.

RiXJ, Heat is a real good way to FIND a bad connection. If you are sure a connection is getting hot, it almost certainly could use a good cleaning. I haven't been "in" to your fuse box, but I've seen posts from guys finding bad connections when gettin in there to look.

 

I'd also check your coil. Once heat soaked they'll have a hard time emitting a good spark.

210-220 doesn't sound all that bad. The electric fan is set to kick on around 220 I believe, so you're in the normal operating range. You might also check to make sure there's no vapor lock going on. Take the cap off the shrader valve on your fuel rail and use a scredriver to push the pin in (kind of like a valve on a tire). If a steady stream of fuel comes out, you can rule any vapor lock out. (Watch your eyes). If theres some fuel, then a bunch of air, then some fuel, etc, you might have an issue with vapor lock.

 

X2, sounds good. I think it's 217-218* (academic!)...Getting vapor from the Shrader valve would seem like a problem, but NOT getting it doesn't rule out the injectors are cooken hot. I might suggest holding a rag there, if you go there.

 

Power washed the condenser, and it seems to be running in the normal operation temp in 90-95F ambient temperature. Didn't have the problems with starting back up.

Thanks for the tip

Now to stress test it on a 700mi road trip :-P

Edit: scratch that, its running cooler, but still heats up at idle, expecting to cut some hood vents for it, and do the cowl intake thing. Every little bit helps right?