I have a situation with my Cherokee where it starts initially and drives fine under hard conditions, and when I stop and turn it off for about 20 minutes, and then start it back up, it spits and sputters and pops until I clean it out by giving it more gas and then it runs fine. I am not sure what this is. I replace the fuel pump, I replace the idle air control I replaced all the fuel injectors, Is it possible it’s vapor lock?

 

Kinda sounds like heat soak.
Any CEL's or pending CEL's?

 

no

 

You running the heat shield on top of the intake manifold?

 

did you change just the whole fuel module or just the pump, have you checked the fuel pressure and done a leak down test, could be an injector or check valve in the tank leaking

 

Research "heat soak". Many threads on this. Not uncommon especially with the 2000-2001 model years.

 

no but I just saw a kit to help fix it so I ordered it today. Heat sheild plus heat wrap around the fuel rail

 

Heat soak stuff:

http://www.wjjeeps.com/tsb/tsb_wj_1803103.pdf

 

If you are talking about the DEI kit that is cool.
Even though I have no heat soak problems in my '00 had I known that kit existed
I would have put one on when I did my 4 hole injector upgrade anyway.
Almost positive that you can't put it on with everything together.
So I suggest buying just the heat shield for the top of the intake manifold first.
See what happens. Problem with that is if it does not work and you buy the DEI kit now you have 2. LOL.
When I did do the 4 hole injector upgrade I did buy a new one. My dealership had one stock.
Charged $2.20 not including tax.
CBXCB060 is the part number for it.
This is the cheapest one I could find and there would be shipping on top of it.

https://www.moparpartsoverstock.com/.../CBXCB060.html

With shipping looks like almost $20. I am in tight with the Jeep Dealership, they are a customer of the auto parts store I work at,
but have no idea why I paid so little. At the $20 price I am rethinking my earlier statement cause now I don't know if it is worth it to buy it to try and see what happens.
Might just be better off biting the bullet and buying the DEI kit.

 

I have done the injector upgrade, I have done the heat soak kit and still had the same problem. I think I have a fuel pressure problem, it just will not hold. Anybody have any more ideas! I am going to fix this one way or another!
I have replaced all the injectors, replaced the fuel pump and had luck for two weeks. I

 

A long time ago I came across this:

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

Which also had a link to here:

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

I remembered it cause it was not the usual regurgitation that guys say, myself included (LOL), concerning heat soak.
To be frank don't really understand it. But maybe you will and it will help.

 

There's a check valve in there somewhere. If it's bad, life is not good. I have not had to mess with mine, so I'm vague on the details, but I do recall reading about it here.

 

Did you get/borrow the pressure gauge to measure/monitor the pressure while all this is going on?

Ralph brings up an interesting point. The CPS and CkPS is out of sync. The CPS has moved out of its window. Instead of



it's doing this



The large blocks are CPS signals the small spikes are CkPS signals. The CkPS signals have to be within a block of a CPS signal. I think you should fully explore the fuel thing like scrubbing up the throttle body, vacuum leaks, etc., but we can go down this road if you want.

 

 

No problem.
If you can understand it and explain it to me in simple terms that would be great. LOL.