Fuel Pump: Description and Operation

Legend

This high pressure in-tank fuel pump is comprised of a DC motor, a circumference flow pump, a relief valve, a check valve, and inlet and discharge ports. The pump assembly consists of an impeller driven by the motor, the pump casing which forms the pumping chamber, and a cover.
If fuel flow is obstructed at the discharge side of the fuel line, the relief valve opens to bypass fuel to the inlet port and prevent excessive fuel pressure. When the engine is shut off, the check valve maintains fuel pressure in the line after the pump is stopped, allowing the engine to restart easily.