2005 Sseries Jaguar Limo, I left the car idling for about 4 hours. Now it will not turn over. I hear something running by the air intake but will not crank it is getting power to it

SOURCE: buick lesabre nightmare

Need to get a scan tool and look at the data stream while it is running for alot more info.Also any trouble codes.Sounds like initially,the engine isn't getting any fuel.I would have a pressure gauge connected to the fuel rail on the engine,so i could monitor the fuel pressure while all this is going on.Items to look at on the data stream would be timing,what timing is the PCM commanding for the engine.Also,have you checked for continuos power feed to the coils during this no start condition,and fire at the plugs while cranking.You could possibly still have spark,but maybe it is extremely weak?I have seen bad ignition switches cause weird problems before too.Many things power up through the ignition switch,just a thought.Have also seen bad PCM's cause strange problems..38 volts is a little on the low side for GM.Usually see those at,at least .50 and up,and rise steadily while pressing the throttle,up to just under 5.0 volts.Potentiometer with 5 volt supply.Vacuum leak can be checked with engine running at a steady idle speed,spray brake cleaner all around the intake manifold and listen for engine speed change.

SOURCE: buick lesabre no start

Hi you have replaced allmost everything ,(try fuel pump relay)

SOURCE: engine looses power going up hill, no check engine light at this time.

How old is the Catalytic Converter, sometimes they will get clogged up and affect performance.
Good luck

SOURCE: hard starting after sitting awhile

if before you start if you hold the gas pedal just a bit does it start faster if it does its our idle air control valve that defective (iac) let me now pierre

SOURCE: 1998 Jaguar XJ8L fuel pump needs replaced.

befor you go to the pump check the relay that might be the problem