Which hydraulic pumps are running after Number 1 engine start?

When the Number 1 engine of the A320 starts, the hydraulic system automatically activates the hydraulic pump associated with that engine, which is the green hydraulic system's electric pump. Additionally, the operation of the blue hydraulic system's pump is also initiated because the blue system is powered by an electric motor that can function independently of the engines.

The green hydraulic system provides essential functions such as flight control systems and landing gear operation, while the blue hydraulic system serves critical functions like the operation of the thrust reversers and some flight control elements. Therefore, after starting the Number 1 engine, both the green and blue hydraulic pumps are operational to ensure that the necessary hydraulic pressure is available for the aircraft's systems.