Fuel Pump: Description and Operation

Fuel Pump:

The fuel pump used is a positive displacement, immersible pump with a permanent magnet electric motor. Fuel is drawn into the pump through a strainer mounted on the bottom of the pump/sender module. The pump contains a pair of check valves. The first check valve relieves internal fuel pump pressure, and regulates maximum pump output by bleeding off excess pump output pressure back into the fuel tank. The second check valve mounted near the pump outlet line restricts fuel movement in either direction when the pump is not operating. This check valve maintains fuel pressure at 48 psi (330 kPa) in the fuel supply system even when the engine is turned off, making it necessary to release fuel pressure prior to opening the system. Fuel pump voltage is supplied through the Auto Shut Down (ASD) relay.