I personally don't use a relay. It is typically switched by the key or by a Power Cut Off switch. I just wire to 12v. The newer electric fuel pumps draw very little amperage. (I have used Facet pumps on three different 80s vintage Plus 8s) They only draw somewhere around 2 Amps.

I reserve relay use fro much higher amperage (eg, 30/60 amps). I would be sure to fuse the circuit, though.

Cheers,

Mark

1934 SS MX4
1938 Series 1 DHC
1951 Plus 4
2005 Roadster