Chevrolet: LT1 Starting issue, fuel pressure guage, jaguar xjs

Question
I have a 95 LT1/4L60E conversion in a 88 Jaguar XJS.  It has recently exhibited an intermittent starting problem.  90% of time it starts fine; almost instantly.  But those other times, usually (but not always) after it has been run then parked for 20 minutes to an hour) (or after dinner with a date) it will not start.  The starter turns the engine over normally, all electronics and lights work, but it will not start.  Then if I leave it alone for 1/2 hour or so it will normally (though not always) start fine.  It has been to the shop several times for weeks at a time until it fails then they have replaced some wiring, given it back, and it is the same thing.  I would like to avoid just starting to throw parts at it but nothing makes sense.  If the distributor died it should not come back.  If the switch or the lockout was bad it should not turn over.  I'm at wit's end and hope you can help.

Answer
Its nothing electrical.

Attach a fuel pressure guage to your motor and tape the guage to the windshield. Start the car and note the fuel psi. It should instantly shoot up past 38 psi. If it creeps up or seems low, its your fuel pump.

A lot of times the check ball in the fuel pump goes and during a hot startup your pump is hot and will not deliver the same psi as a cold pump.

Don't let your tank go below 1/4. The pump uses the fuel to cool itself.