2000 Jeep Cherokee, 4.0.
For 3 years it's never missed a beat. Never failed to start, always ran like a top.
Parked it at the house the other night, next
morning it cranks but won't fire.

I removed the air snorkel and sprayed some starting fluid in the throttle body. It would
then *sort* of fire - weekly. Not like a brief
rev up like you usually get with ether. Still,
there was some sort of ignition - very brief,
and never after key was released from the start
position.

There's a "test" schrader valve on the fuel rail.
I pressed it and a little fuel came out under some pressure, but less than I expected.

Any theories?