Couple things to note: It's only ever stalled while driving once. But that may be because I don't really drive it anywhere anymore. I know I'll be stranded for an hour or two if I do. Even when I had a no start condition the CPS metered out okay.

Second, when it won't start, no amount of cranking will ever clear the injectors (if that's whats happening). I can crank it until the battery is dead and it still will not start.

I think the next logical step is to wrap the exhaust manifold in an attempt to reduce underhood tempatures. Anyone agree?

 

A bad crank position sensor would cause a no start condition. You need to check into that.

And as far as heat soak, wrap the injectors, not the exhaust.

 

Seems to me if the starter is spinning the motor, fuel pressure builds while cranking and the injectors are squirting, then maybe there's no or weak spark at the plugs due to something changing electrically when hot.....maybe the coil?

I thought 99.9% of the heat soak affected XJs were the '00-01 models......the 2 years with the twin super hot cats directly under the intake, no?

 

Yeah, definitely sounds like something else going on.

 

Yea, but I thought it was more to do with the newer intake design, which is what I'm running. Maybe I'm wrong about that. I have moved away from the idea that it's something electrical when I was able to get it running by pouring fuel into the throttle body. Wouldn't that seem logical? I wont rule it out completely, just don't want to keep chasing my tail and spending money I don't have.

 

The '00-01 models have the super hot twin cats directly under the intake so there's way more under hood heat than '99 down XJs that have the one cat under the passenger floorboard.

Does sound like a fuel issue if adding fuel direct allows the motor to start..... I thought I read earlier that fuel pressure was good when cranking the motor, maybe I misread. If fuel pressure is good while cranking, seems like any air ahead of the injectors would quickly be displaced by fuel and the injectors would be squirting unless something (heat or electrical) is preventing the injectors from opening.

 

The fuel vaporizing almost sounds believable, but I'm trying to not narrow my field of view to just that. Yesterday while testing the fuel pressure (which you read correctly, its appears to be great) I grasped one of the fuel injectors while I had my Dad crank the motor over.... I'm pretty sure I could feel the injector clicking.

Looks like I'm going to have to go get a can of gas because this is going to require more testing and I don't trust it to drive to the gas station...

And if you're thinking right now that I have a low fuel/dirty fuel problem, don't. There are a few gallons in it and I completly cleaned the tank when I put the new fuel pump assembly in.

 

Never crossed my mind.....I would think enough gas in the tank would be a given.

 

yea i "wouldn't" rule out spark either, just check the spark its free make sure its right color and strong.....dont rule out starter, does jeep make any loud noises when your trying to start it?

 

Sort of. I'm back to concentrating on the CPS. Wish I had money to throw at it so I could just buy a new one and be done with it.

I did a new test with an O-scope and watched the wave form of the CPS. What I found was the signal skipped every so often.... and seemed to increase skipping the hotter it got. Funny thing is, now it seems to always start. I have not driven it at all, but it won't "not start" anymore. So in a way it's fixed it's self. CPS is still on my list to replace next.

 

I think I would be looking to see a good spark. I don't remember seeing fuel problems cause a no spark.

 

That shouldn't happen. CPS can become heat sensitive, which yours appears to be doing.

 

well guess what i would do... go to auto parts store see if you can return the CPS if you end up not "needing it" then if you try it and everything is fine good to go if not return that sucker and say you didnt need it. just a thought.

 

Well no **** there I was! Fixed my damn jeep! Couple problems were happening here! The coolant temp sensor code was not due to sensor or the fact i removed AC it was a worn connector on pig tail also back fire and spit was due to same problem on IDle air! So on top of that the CPU was messed up! So runs great and no more light!!

 

Sounds like the same problem I'm having right now. Starts great when cold everything seems normal but if I turn it off once it is hot it won't restart unless I hold the gas peddle to the floor. Someone said fuel pump or the screen or fuel filter. Need to check fuel pressure. I forgot to say once I get it restated when its hot it turns on the check engine light. Mine is a 95 4lt Sport. I had the engine out for a little front end damage repair. I have recheck all grounds and connections all seems right. Also i seem to have a knocking sound now between 1000 and 1500 rpms. I also installed a new exhaust manifold but that seems to be good, I have rechecked all bolts for proper torque specs.

Sorry don't mean to high jack your post but sounds just like what i have going on, at least part of it.