Engine Fuel Pumps

021-10-03Pablo Asensio Martínez2026-03-241 min

Auxiliary Pumps

  • Type: Usually electrical (not engine-driven).
  • Function:
    • Backup: Parallel to the main engine-driven pump.
    • Vapour Lock Prevention: Pressurize fuel lines to suppress vapor formation.
    • Priming: Used for engine starting.
  • Operation:
    • Normal: Switched ON for takeoff and landing. Switched OFF in cruise.
    • Abnormal: Switched ON if main pump fails or vapour lock is suspected.

Fuel Injection System Pumps

  • Principle: Delivers fuel under pressure directly to the cylinders (injector assembly) rather than relying on a venturi (carburetor).
  • Engine-Driven Pump:
    • Supplies fuel at positive pressure to the injector assembly.
    • Pressure is often determined by engine speed.
    • Excess pressure is returned via a relief valve.
  • Advantages: Uniform delivery, better icing protection, quicker throttle response.
Written and reviewed by

Pablo Asensio · 2026-03-24

Aeronautical engineer. Passed the thirteen EASA ATPL(A) theoretical knowledge exams studying from these very notes. Writes and reviews each topic against the Part-FCL Learning Objectives.

Suggest a correction

Related topics