Jeep won't start when hot

My jeep hasn't started when it's hot (after its been running for a while) now for a few months. It will just sit there and crank and crank. Let it sit for a while and it's fine. The first time it happened I replaced the spark plugs, wires, distributor cap, air filter, and fuel filter. Worked for two days then wouldn't start when it's hot again. It's a '91 Cherokee with 200k miles on it. When it won't start I've checked for spark while cranking it over....nothing even coming out of the coil, checked the cap just for kicks and nothing there either. I replaced the CPS on it yesterday thinking that was the problem, still won't start when it's hot. I've gone into several different auto parts stores (advance, autozone, napa, etc) and i get the same thing, "a friend of mine has a jeep and this happened to his, it's a common problem, you need...." and they try and sell me new plugs. One thing I have heard is the Ignition Control Module is going/gone bad and when it gets hot it doesn't respond well to starting. What really gets me about it is it still runs fine when it's hot, no loss of power, no lagging, jolting, lurching it runs just fine. So to all the Jeep gurus out there, is there a magical dance I can do or maybe even a special place I can hit it with a hammer to make it be perfect, because that would be awesome. If not, is the ignition control module the cause of all my problems here? Thanks for reading this far and hopefully y'all will be able to figure this out for me.

PS I did the search and didn't come up with any "not starting when hot" threads so if they're out there please let me know and i'll start over again there.

91's had problems with coils back in the early 90's. maybe your is finally going out

Thanks for the responses yall. Ill try that and see how it does

Also check the CPS.

Check the wiring to the auto shutdown relay and the relay itself.

I don't have my manual in front of me but if i look up "auto shutdown relay" will that show up? Because I have never heard of that and therefore have no clue where it is or what it would look like.

Try getting a used coil and ignition control module from a buddys jeep and put them on take it for a quick spin and then park it and try starting it again. I had that same problem and thats what it turned out to be. After running it and shutting it off the coil and ignition control module get heat soaked and they stop working until they cool off alittle.

I don't know if this could be it but it's worth a look. http://www.naxja.org/forum/showthrea...ight=heat+soak

The auto shutdown relay is what the computer uses to power up the ignition coil. Sometimes wires get some corrosion and when they get hot they get more resistance, I have heard of the relays doing the same thing. I don't have my manual in front of me either but it might be worth looking up where the relay gets power and grounds and checking volt drops if the coil doesnt fix the problem.

Los Lobos said:

I'll second the coil.

Click to expand...

3rd.

It will get hot and won't work, mine did that and it drove me crazy. I replaced a ton of stuff before that.

ignition module underneath the distributor cap. Typical problems as it heats up it breaks down and loses spark.

Sorry it's been so long to get a response back, school's just started back. So I replaced the coil a few weeks ago....that wasn't the problem so i took it back. I just bought a new distributor and "cam pick-up sensor" today. I'll put it in this weekend and give it a little drive and see how it does. The guy at autozone actually knew what I was talking about when i went in to buy this one so hopefully this will work. Thanks for all the responses and help so far.

Final verdict...replaced the distributor and it wouldn't start at all. No spark whatsoever. Spent two days messin around with it...then just took it to the shop. Thanks for all the help y'all but I think I think i might have been in over my head this time.

Hey, let us know what is going on when you get it back. Mine has been doing the same thing for some time. Thankfully it hasn't been as hot this year so I haven't had to deal with it

Got it back yesterday from Tanner. Talked to the guy who worked on it and he said that I had a bad distributor in it (the one i just bought). So that was the final verdict on that one. Thanks for all the input guys

well, I had the same problem on my 97- 4,0L. Problem came from suction fals air where the fuel tube is hooked up to intake manifoil. Had a few month earlier tighten up the plastic strip patent thats on the rubber fuel tube. Stupid patent!
Replaced the strip and everything has been perfect since.

Just to give you guys a hint witch have gone the path of replacing all ingnition parts and still not quit the problem.