2001 s40 will not start. When you turn the key you hear the starter motor turning over but the engine does not catch.

This has happened a few times very infrequently over the past year, but has always started after letting it sit for a few minutes. Sometime In January this happened and it would not start after 15-20 minutes. Left it alone for a few hours and it started fine. no issues since then until...

Sometime last week was the last time it started, Took lots of engine cranking, idled rough and then died. Has not started since.

I replaced the fuel pressure regulator after reading people with similar issues on the board, but it still will not start. Fuel rail was pressurized so I assume the fuel pump is also fine.

 

Crank the engine while holding the throttle open just a tad with your foot. If it starts then I'd be thinking Idle Air Control motor. If not then I'd check actual fuel pressure. If that is ok then remove a spark plug and check for spark. I would also check timing by lining up the timing marks on the cams and crank to make sure that is good.