I used sort of a reversed setup on my fuel pump when I had to switch to an electric from a mechanical. One device hooked up to two different sources of power. The fuel pump positive wire is on 30, 87a is hooked up to the starter circuit (power to pump only when key is to start) and 87 is hooked to a keyed on cicuit (power only when key is ON). The coil (85 and 86) is hooked to a feed off the engine relay that has power only when the motor is spinning. It took me a while to work it all out, but now the pump only runs if the key is turned to start or the motor is running. No runaway gas leaks in an accident or if the motor dies when I leave it idling.