What function does the primary jet pump serve in the fuel system?

The primary jet pump in the fuel system is essential for maintaining the flow of fuel from the fuel tank to the engine shortly after engine start. This pump operates based on the Venturi effect, using the pressure difference created by the engine's operation to draw fuel into the engine’s fuel lines. It ensures that the engine has a continuous supply of fuel for combustion, which is crucial for a smooth operational initiation. Maintaining proper fuel flow post-engine start is vital to prevent engine stalling or starting issues, highlighting the importance of this component in the fuel system.

Other functions mentioned, such as fuel transfer during standby, fuel cooling, and fuel measurement control, are important in their own contexts but do not directly represent the primary role of the jet pump after the engine has started. The jet pump does not typically handle fuel cooling or measurement; those functions are managed by different components within the fuel system.