Main fuel relay is located high up on the RHS of the steering wheel under the dash.

Remove the plastic kick panel under the dash and then look up above the fuse box - its held in place by a 10mm bolt and is clustered with the other relays up there.

Simplest removal is to grab the wires connecting into the MFR and pull down on them whilst using a screwdriver to pop the side of the MFR cover. The MFR in these cars is normally a rust red colour and the connector is sufficiently strong enough to take this process.
Make sure you disconnect the battery as there is positive power to the MFR at all times.

Replacing due to no fuel pump running? Cracks in the solder are very normal in these ones.