ummm the earth as Duane said, comes from the ECU
The ECU pulls to ground when the it switches on the Fuel Pump
it initially primes it for 2/3 seconds with you switch on the ignition, then starts it again when you start the car.
There is no sensor to pickup fuel pressure or what not, check if you don't maybe have a loose wire or a short.
On the passenger side, there is a white plug just under the clove box, the fuel pump wire goes there and then into the ECU harness. What wire I can't remember exactly... think it was white or orange... really can't remember, rather check the service manual
Check with a Multimeter if you get continuity between that wire and the body initially when you switch on the car, that should last only a few seconds then why you start it should give you a continues continuity if the wire directly from the ecu pulses you might sit with a buggered ecu.