Basically, electric fuel pumps are available in various designs, pressure capabilities, flow ratings, and applications, all of which depend on specific types of engines. Two of the common types of electric fuel pumps include in-tank pump and in-line pump. In the case of an in-tank pump, it is located inside the fuel tank, totally immersed in gasoline to help cool and lubricate it when in operation. These pumps generally operate within the range of 40 to 80 PSI, which is sufficient for most fuel injection systems, and eliminate many vapor lock problems since they are submerged in the fuel. In contrast, inline pumps mount along the fuel line outside the tank and offer ease of replacement or upgrade but, without the direct cooling by fuel that an in-tank pump receives, tend to overheat.
Not all fuel pumps are created equal, as some also have different flow rates: 200 liters per hour for a standard pump should be adequate for almost all normally aspirated engines. For modified or forced induction engines, however, high-performance electric fuel pumps go upwards of 300 liters per hour or more, taking care of the needs of heavy torque and in excess of 400 horsepower of power. These high-flow pumps also by brand names like Walbro or AEM on the other hand, are turbocharged or supercharged application-specific with fuel demands up 30-40% above that of naturally aspirated engines.
The voltage requirements also serve to further differentiate electric fuel pumps. Standard pumps operate at 12 volts, drawing about 10 to 15 amps in operation, while high-performance variants may require more amperage as a means of supporting the increased output of a given pump. Ensuring that the wiring and relays are compatible helps in ensuring that these higher-capacity pumps can operate reliably without electrical issues. Certain fuel pumps operating in racing applications have voltage boosters that help reach higher flow rates and sustain consistent fuel delivery at high speeds with the intent to maximize an engine’s power output.
Some of them have ethanol-compatible pumps made to resist the corrosive effects of ethanol-blended fuels that can ruin standard pumps. Of course, said ethanol-compatible pumps, usually manufactured with stainless steel or with special rubber components, would be needed for any vehicle that would use E85 or other high-ethanol fuels that could reduce pump life by an estimated 20-30% without the right materials.
Unlike older designs of constant-speed pumps, variable-speed electric fuel pumps change their flow rate according to the demand of the engine. Because of this, it reduces wear and increases efficiency. By changing their speed, these kinds of pumps reduce fuel consumption and electrical load during low-demand situations such as idling. This functionality enables precise fuel delivery for both performance and efficiency, often featured in high-end models.
The right Fuel Pump choice will depend on the type of engine to be utilized, the amount of horsepower required, and the type of fuel to be used. Each pump type offers unique benefits that will meet certain performance and durability requirements.