Hyundai 31111-25000 Fuel Pump

Check the fuel tank and fuel pump, listening for a whirring noise when the ignition is on. If silent, inspect the EFI fuse, circuit, relay, and fuel pump cut switch. If these are fine, examine the fuel pump wiring. Test fuel pressure by connecting a fuel pressure gauge between the fuel supply line and fuel rail. For return-type systems, check fuel pump operation and pressure with ignition on. If pressure is high, inspect the vacuum and fuel return hoses. If low, pinch the fuel return hose and replace the regulator if pressure increases. Disconnect the vacuum hose to check regulator operation. For returnless systems, measure fuel pressure while the engine is idling. If pressure is low, check the fuel supply hose and line, replace the fuel filter or fuel pump/regulator. If high, replace the fuel pump/regulator and diagnose the fuel system. After testing, relieve pressure, disconnect the battery cable, remove the gauge, reconnect the battery, and check for leaks.