The Buick Electric Fuel Pump is now required on all vehicles because of the type of fuel delivery systems that are now utilized. The days of the carburetor and a manual fuel pump are long past. Today a consistent level of pressure has to be constantly maintained in the fuel delivery system for the fuel injection systems to operate at peak capacity.
Because the Buick electrical fuel pump provides a constant level of pressurized fuel to the system, its exact location can be anywhere in the system. The most common place is in the fuel tank. This makes it possible for the electric fuel pump and its sensor on your Buick to push the fuel forward and be easy to maintain. The older type of mechanical pump was mounted on the engine and basically sucked the fuel from the tank and moved it forward by creating a vacuum in the system.
This new approach to providing fuel to the engine with an electric fuel pump makes it possible for the pressure to be maintained at a constant level during the operating of the Buick engine.
Other difference between the electric fuel pump and the older mechanical type is when the system contains pressurized fuel. The mechanical fuel pump only provides its pumping action when the engine is turning over or running. The electric fuel pump operates when the ignition key is turned on. For this reason if the fuel system is to be opened, like when the fuel filter is being replaced, the ignition key must be turned off or fuel will squirt out of the fuel line and create a hazardous situation. This is true for all Buicks with this type of fuel delivery system.