i only read the first paragraph because the fuse powers the fuel pump relay and the fuel system relay in the 83-84 240. replace the fuse holder and make sure the connections are tight. the 2 relays are under the glovebox. i'm betting the supply from the fuse or the supply to the fuel pump-yellow/red is loose or melting out of the relay socket. once everything is squared away, check the current draw, could be the main pump is dying and drawing too many amps or the tank pump has died and the main pump is suffering from fuel starvation.

there may be other problems in the car. too early too tell. good luck, chuck.