Fuse #7 powers the RPM relay, FV and Lambda ECU. The RPM relay output powers the fuel pump and WUR heater and one relay coil.

So rewiring the RPM relay input power to it's own fuse will eliminate the FV and Lambda ECU power. My guess is the FV and Lambda ECU power is about 2 amps.

The WUR has been know to short circuit (did it on my car). That may be one reason that the #7 fuse can melt.