Hey guys,
I have been lurking around on here for a bit and I haven't really been able to figure this problem out so I figured that I would ask. My girlfriend has a 2000 cherokee sport 6 cyl automatic and on hot start on hot days (75* F+) the car will stumble and sputter occasionally stalling for about a minute before making any power then it just goes away. I did the normal work of new plugs and a new crank position sensor with no improvement, I don't want to keep throwing parts at this but she is worried it will leave her stranded some day. Does anyone have any suggestions?

 

Maybe heat soak causing vapor in the fuel lines.

 

I considered that however I don't know what I can do about it, any suggestions?

 

The link I posted is to a couple heat shields that are made to help with heat soak.
Others have added hood vents to help.

 

Sounds like heat soak to me. Mine seems to get worse every year. Going on 7 or 8 now but it has never left me stranded. I'm upgrading the entire cooling system this year so maybe that will fix it.

 

wow I'm sorry I'm blind, I didn't see that there was a link there. thank you for the suggestion.

 

The 2000 has cast iron manifolds which hold the heat and cause the fuel in the rail to boil. My 2000 WJ 4.0 has the same manifolds but has never given me the same problem, however there's a lot more room around the engine in the Grand for cooling.

 

wow that's an interesting design choice. Is it common for these to have vapor lock issues? I have never really heard of it in FI vehicles before. Is it possible there is a lack of fuel pressure and the vapor lock is just a side effect? I'd hate to put a bandaid on the problem with those DEI heat wraps above and then find out that its really a fuel pump or regulator

 

Common enough for Jeep to put out a TSB about it. There has also been threads around that have discussed lack of fuel pressure causing the issue. Does her Jeep have the California emission pre cats on it?

 

While I own a CA Emissions '00 in 7 years have not had any heat soak or misfire issues.
Knock on wood.
I just posted this awhile back. Came across it in my travels in internet land a long time ago.
Not the usual stuff concerning heat soak.
And to be frank really don't understand it.
Anyway,

https://www.jeepforum.com/forum/f11/...think-2975897/

And there is a link in there posted that leads you here:

http://jeep.blackonyx.net/pdfs/jcss.pdf

 

It does not have the CA emissions.
I looked up the issue and saw the TSB about it after it was mentioned, crazy to think that its able to get that hot. I picked up some spark plug wire heat shield covers and I'm going to try those this weekend. I don't think the $50 kit is worth it as this is an all stock 00 with 330k on it and it isn't ever wheeled or anything. But I am hoping that fixes the problem. I will report back on the next hot day we have. I also have to fix a bunch of wring in the drivers door while I'm at it since she has no drivers side speakers and the door lock wont work with the door open. gonna be a fun day. Her car is getting more love than mine gets right now

 

I am not getting any miss fire codes and it isn't lacking power or doing a continuous miss fire like if it was out of timing but if the heat shielding doesn't fix the problem I will give that a look thanks for the heads up

 

ok so the injectors and fuel rail were already covered in her jeep, my fault for not looking, at 330k she may just have to live with this issue.

Also wow those drivers door wires! 3 broken, and at least 4 more with the sheathing worn through!

 

I'm sure others will have some more input on how they dealt with heat soak, assuming that is the problem.

 

I'm sure that I could however the problem is that the number 3 connector started to fall apart as soon as I touched it so I don't want to risk pulling the injectors. Honestly I forced it to vapor lock today and tried a solution I found of leaving the key in the on position 3 times for 5 seconds each and it did help a lot. I think that is the best option at this point, she doesn't think its worth a fuel pump if the check valve is bad and I don't think its worth ripping injectors or connectors apart so it may have to just survive as is