Can you get a gauge first? Its a pita to pull the pump.
With a gauge you should see this:
key on - full pressure (39psi????) whatever the spec is
Crank and start- it will drop a little as it starts and then hold steady
shut engine off- it should hold pressure
if it has leaked down- turn key on and it should go back to system pressure
I would try to duplicate the problem and do the starting fluid trick, it will tell you a lot. When you say it wont restart, do the starting fluid trick then also. While someone is cranking it over shoot it a little and see if it fires. Your trying to pin point fuel or ignition. When it has run and wont restart, pull a plug wire, put a screwdriver or something in the boot and hold the screwdriver near the block and see if it has lost spark at that moment. I don't know your ability, and I don't want to sound like your Dad, but be careful, have a fire extinguisher around. Just don't want to see your garage burn down. Just as the engine can run when fuel and ignition are provided, your stuff can burn to the ground also.