Fuel pump relay a protection for the circuits and control the fuel pump relay controls the electrical current going to the force pump from the vehicle. The relay operates on 12 volts in the vast majority of cars, and acts as a sort of “gate,” allowing a small ignition switch current to control a larger current going to the fuel pump. By moving high currents away from the ignition circuit, this helps to avoid a destructive overheating issue and a possible short circuit.
While fuel pump relays are generally rated for currents from 15 to 20 amps, the entire current that it takes to run the pump would have to go through the ignition switch without the relay, which would wear out the ignition components quickly and cause electrical failure. In high-demand applications (like sportscars or heavy-duty trucks), a properly functioning relay becomes critical to supply the high power demands of larger or high-performance fuel pumps (often rated at >40 psi pressure output).
Relays also act as a safety device, triggered to turn off power to the fuel pump under certain circumstances. In the case of an engine stall or crash, some relays cut off power to stop fuel from pumping in order to minimize the possibility of fuel leakage or fire. In fact, lots of the so-called electrical alarms nowadays come pre-built with crash detectors to instantly shut down the gasoline system on the time of a crash, a requirement put in place in vehicles after various authorities such as the National Highway Traffic Safety Administration (NHTSA) did need to afford better in-crash automobile safety.
As automotive authority Scotty Kilmer elaborates on that topic, “A fuel pump relay does more than just supply power to the fuel pump — it supplies safe controlled power to the fuel pump, and in turn protects your whole fuel system!” While it is crucial for drivers, the Fuel Pump relay also helps preserve effective function in the vehicle electrical system and fuel system from many possible threats.