run a 20/30amp live supply straight from battery make sure its fused batt end, take same size cable for a neg too, find fuel pump wires in boot, the pump 12v is red / black iirc, take the neg from batt straight to pump, get a 30amp relay run new feed to relay, earth relay to chassis, live from relay to pump and use the original pump live to turn relay on, relay has diagram on it so quite easy