2000 XJ runs great one night, and next morning cranks but won't start

Geez, its one thing after the next. It ran great on Saturday night when I went to go pick up some shelving. Sits all day Sunday, and then Monday I decide to use it to drive my kid to school. Starter cranks perfectly but absolutely no sign of life. No smell of fuel in the tail pipe but I can hear the the fuel pump go through its priming cycle before I crank the starter. I put a fuel pressure gauge on it, and the priming cycle is enough to hit and hold 48-49 psi.

I disconnected and reconnected all sensor leads, refreshed the grounds that I haven't yet refreshed, pulled the cam position sensor (looked fine), but still cranks without starting. I guess this is pointing to the CPS, but pretty crazy that it works perfectly and then totally dead the next time I try to use it.

I picked up a NAPA Proformer CPS this afternoon, and I have a Mopar CPS on order from Amazon. Hoping to try the NAPA sensor this evening.

BTW, no OBDII codes.

It was the stupid CPS. Fired right up with the NAPA Proformer.

Those CPS are finicky Sometimes they go out intermittently and sometimes they go out in the dead of night!
Glad you found the problem!

Sig220 said:

Those CPS are finicky Sometimes they go out intermittently and sometimes they go out in the dead of night!
Glad you found the problem!

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Apparently. And the failed sensor did not exhibit a short across the B-C terminals, so the only way to check for bad CPS was to replace it. Glad the NAPA CPS worked. And now I'll have a Mopar as a spare.