Not starting

97XJ 4.0 4WD 185K

Yesterday the temperatures reached 100F in CT where I work and after baking all day my car wouldn’t start. I thought it was the fuel pump, because I couldn’t hear it, you know how you hear the fuel pump before the starter turns the engine… which made me mad, because my fuel pump is less than two years old. So, the symptoms were: Not hearing the fuel pump, engine turning and acting as if there isn’t fuel, all dashboard lights, fans and radio coming up.

It was towed and I got a call today from the service center that it had started. They think it is the computer, because it died on them once and they “were not seeing any spark” during that time. Apparently at some point it started and now they “cant make it die again”. They were expecting that the computer would throw out codes, but none so far.

Anyone had this bizarre problem? Where should I have them look?

Thanks in advance.

Best

Boris

Crankshaft Position Sensor is fairly well known for a heat soak intermittent death. When it fails, you won't get any spark, or fuel.

X2 on the crank sensor.

Thanks for the fast reply, guys.

How often do these sensors fail? Mine is no more than three years old, I replaced it as part of preventative maintenance.

I've replaced 1 CPS on my 94, w/ 230k miles on it. They don't fail often.

I replaced the cps on my 89 (26000kms) a couple of weeks ago for just this fault.
It wouldn't start when it was hot out or the engine was warm, but when it was cold outside it would fire right up..
If i let the engine idle to normal temperature and then shut it off it would refuse to start until it had cooled down.

Genuine Jeep CPS last about 100-150,000 miles. Cheap crappy "lifetime warranty" CPS can be faulty right out of the box, or can have failure anywhere from after few months, to after few years.

Test the CPS, when it won't pass the test, or you have a CPS related no-start, you replace it.

I just got a call from the garage where my car is.

I was told that they "got to the bottom of it". They found out that one of the wires supplying power to the computer didn't have any voltage. That somehow was connected to a wire in the fuse box whitin the cabin and it has to do with the way the "aftermarket sunroof" was wired (there is a jumper in the fusebox, I dont remember what its function is)

Does this sound like a plausible story, or they just couldn't find anything and are still charging me $181?

Are there any questions that I could ask when I go to pick up the car in order to find out if they are lying?

Thanks in advance

Got my car back.

Based on the further explanation I got, I feel very comfortable with these folks and believe that they did an outstanding job. If anyone needs recommendations for a shop in the Windsor, CT area please, contact me and I will give you the name.

Also thanks to all of you who responded.

Best

Boris