There is a complete circuit diagram of the fuel pump relay, fuel pump circuits in the Service manual electrical section on page 17-39. There are three wires connecting the relay, one is from the ignition switch, the other is from the ignitor and the third wire goes to the fuel pump. My interpertion is that the ignitor signal permits current flow from the 12 volt input from the ignition switch to the fuel pump positive lead, so that means the engine ignitor must be fireing (engine running) in order that the fuel pump runs. The Fuel Pump Relay is not a common solenoid type relay. The original fuel pump also appears to have a pressure sensitive cutoff switch built into the fuel pump, that relieves the pressure on the float needle valve, when the float bowl is full.
I could be wrong but that is my observation from the service manual information.