Welcome to the forum Tom.
Hope you'll stick around after you see hpow fun this one is.
Your symptoms are pretty much the definition of a code 54.
Easy things first, and I don't think you have a cutoff sw.
Check the connection at the oil pressure switch,
they have a habit of getting bumped loose.
This is my bet. Some are simple sw, some are combo sw&press-sender,
does not matter if not tight connection.
Second, check the relay for function with your finger on it when the key is turned to on.
Should be able to feel or hear click.
Third, pull they relay and check for batt voltage to it from
fusible link by checking it's hot at relay plug (think pin A, org?)
This would cause no hot anywhere for fuel pump stuff.
If good, may want to try swapping the brake lamp relay for it if you have one.
Make sure relay installed again before moving on.
Fourth and you want to be gentle here, check for voltage at the DLC (ALDL)
Look for batt voltage at pin G, believe lower left of connector,
while cranking the engine enough to get about 5psi or more oil presure.
Relay is only supposed to work for the first few seconds of cranking
and as oil pressure comes up, the fuel pump gets power through
the oil switch. That's when the DLC will be hot also.
Code is set when PCM sees low voltage on pump anytime, so does not tell
if relay or oil press circuit, Big help since you know the gas isn't moving.
BTW to clear the code you can wait through about 50 start-ups,
or after fixing the problem, clear yourself by disconnecting battery for a while.
Post back what you find. Good luck.