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Home >> BMW >> 1983 >> 633CSi Standard >> Repair and Diagnosis >> Engine Performance >> System >> Fuel Injection System - BOSCH AFC >> Description >> Electric Fuel Pump
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Electric Fuel Pump

The fuel pump provides fuel under pressure to the fuel pressure regulator. Power for operation during cranking mode is provided from starter relay via the fuel pump relay. After the engine has started, control of the fuel pump is by a fuel pump circuit in the air flow meter.

The first movement of the air flow meter air measuring flap (about 5°) closes the fuel pump contacts and provides power to fuel pump after engine has started. With engine stopped, no air flow is present, measuring flap closes and fuel pump contacts are opened to cut power to fuel pump. This circuit reduces the risk of fire in a collision. The fuel pump is a sealed unit. No service is required.