Ive had extenisive exp. with similar issues of no start, on an intermittent and increasing basis. I confirmed it was fuel supply by using start fluid which fired the engine right up. But I never had the excessive consumption you have.

Yes check the relays to the pump and fuses..And that OVP relay is a common cluprit on these cars. It kills everything.. But if yours cranks its likely not the OVP relay. Try starting fluid and it may fire right up.. Then check the pumps.

This car has dual tandem fuel pumps and they fail intermittently and will work when tested then not work..And both will fail at the same time. It will run on one only and I suspect failure is often the little check valve becoming obstructed with corrosion out of the tank..and this s pre-filter so you might pull the pumps and test and just clean or change the check valves before replacing. Theyre both very easy to remove and replace..