Here is my issue. If jeep sits for a half hour or more it starts right up. Take it to the store turn it off when you get back in turn the key fuel pump comes on it cranks over but will not start, leave the key in the on position for about 3 to 5 minutes crank it over it starts right up It does not appear to be a vapor lock situation because at times the engine does not even reach operating temp. its got me puzzled

 

Crankshaft ignition sensor. Seems like a common problem in XJ's especially if it's never been replaced. Don't run to the store and buy one; but mine would turn over i unplugged it, plugged back in fired right up. Try it and see

 

x2

same thing happened here unplug and plug it in it worked and havent had any probs yet and that was 3 months ago

 

Its not the CPS that is causing the problem have unplugged several times and also replaced and even unplugged new one it still happens everytime.