Fuel pump
Fuel pump
The fuel pump is located inside a plastic reservoir that is fixed between the top and bottom of the tank. It is centred on ribs on the bottom of the tank and secured to the top of the tank with a screw ring (10).
Movement in the tank is taken up by the fuel pump spring (9). In principal, the design and function of the pump is no different to that of earlier fuel pumps with a main and feed pump. In the Walbro pump, however, the feed pump has been replaced by a positive ejector that is "driven" by the fuel flowing from the delivery line via a T-piece. The pump is an electric rotor type pump.
Fuel pump location in tank
The ejector is used to secure the supply of fuel to the pump. Thanks to it being located in the reservoir, the pump is guaranteed a flow of fuel even during cornering and acceleration with small amounts of fuel in the tank. The pump and motor are encapsulated and cannot be dismantled for repair.
A non-return valve on the pressure side of the pump, located in the connector nipple in the pump cover, prevents the pressure in the fuel line from dropping as soon as the engine is turned off.
A modified fuel pump unit has been introduced on M01 cars to reduce exhaust gas emissions when starting. The fuel pump is equipped with a non-return valve at the ejector inlet to ensure the level of fuel in the pump reservoir is maintained as high as possible, even when the level in the tank is low. This allows the starting fuel pressure to build up faster and provides more reliable starting and consequently reduces exhaust gas emissions. A fine-mesh filter is located at the inlet to the non-return valve to protect it from dirt.
