When the demand to supply fuel rises, as for example when the fuel level is low, or a filter is clogged, or there is an electrical problem with the pump, or the engine has had modifications that demand more fuel flow than standard specification, the pump can be overworked. When you run the fuel tank down under 25%, the pump actually has to work harder because the fuel is the coolant for the pump, and it actually helps dissipate some of the heat generated during its operation. The pump runs hotter, which makes it less efficient and can shorten lifespan by as much as 30% in high-mileage cars when there's not enough fuel helping to cool it down.
Clogged fuel filters are one of the biggest culprits for causing an otherwise healthy pump to strain. Filters capture contaminates protecting the fuel system, but the more clogged they become the more pressure the pump has to make to push the fuel through the narrowed opening. In fact, clogged filters can increase fuel pump demand by 15-20%, which has an efficiency penalty and can cause premature pump failure. To prevent excessive buildup of contaminants and ensure a smooth fuel delivery, mechanics recommend changing the fuel filter every 30,000 miles.
Another component that contributes to poor fuel pumps working too hard is electrical issues — like low voltage or bad wiring. A good, steady 12-14 volts are necessary for these pumps to operate properly and if voltage drops, due to corroded wiring or a dying battery, the pump won't be able to keep up with the pressure. Most failures (10% of the pumps out there) are avoided because those electrical problems are discovered early and resolved, avoiding unstable voltage and pump failure.
For high-performance applications, factory fuel pump does not work properly because in a high-performance setup those engines call for fuel flow in excess of 250 litres per hour (LPH) at 43.5 psi (3 bar). Performance mods — turbochargers or higher-flow injectors, for instance — raise fuel requirements to levels beyond the design limits of the pump. To satisfy these demands, a high-flow Fuel Pump should be installed, which allows for sufficient fuel flow without straining the pump too much, which helps support consistent performance and reliability in demanding conditions.