Fuel Pump: Description and Operation

Roller Vane Fuel Pump - Exploded View:

Fuel Sender Assembly:

Two electric high pressure roller vane fuel pumps are attached to the fuel level meter assembly. The primary pump is in operation whenever the engine is running. The secondary pump is used only during cold cranking and operation, during periods of secondary injector operation, and during periods of engine operation when a Code 14 or 15 has been stored by the ECM. A sump in the tank, located beneath the fuel pumps, assures a constant supply of fuel to both pumps even during low fuel conditions and aggressive vehicle maneuvers.
The electric fuel pumps are controlled by the ECM through individual fuel pump relays.