Cadillac Seville / Cadillac Eldorado Forum Discussion, 1997 SLS - maybe not the fuel pump thats bad? in Past Cadillac Vehicle Discussion; Test the gas pressure with ignition ON and engine off.
Compare it with the fuel pressure w/engine running.
Check the ...
Could it be the fuel pump relay being you stated you can cycle the switch several times and it works?
Typically or from what I've experienced the fuel pump quits all at once and usually on a cold start never to pump again. Maybe, just maybe you can rap the tank one good time and get it to kick in but I would only trust it to get it to where I was goinf to repalce it.
I had one repalced in a Yukon awhile back and it was aournd $800-850 at a dealership but luckily under warranty.