The first electric fuel pump circuits were very simple. The pump circuit usually involved a relay and fuse. The control side to the relay was typically wired to an ignition circuit or key switch. The control of the fuel pressure was performed with an analog regulator that could keep a static pressure and adjust for loads with a vacuum signal.
This forced the fuel pump to operate at full battery voltage the whole time no matter the load on the engine. This is not good for the life of the pump. In the early 1990s, vehicles had circuits that used resistors controlled by the engine control computer to slow down the pump and extend its life. These systems operated like a blower fan motor controller.
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