It does look like the fuel pump controller is faulty René (I hate to call it a relay). Note this is driven by an FPC signal from pin 81 on the ECU (white wire) to pin 3 on the controller so check these connections which run through via chassis loom.
Note there is no monitoring feedback though for +4. On my similar age Roadster which uses the same controller, an FPM signal from pin 7 sends this data back to ECU for greater integrity I assume. It doesn't have need for a high pressure fuel pump though.
