What type of pump is used in the fuel oil system?

• A. Vane type
• B. Gear type
• C. Diaphragm
• D. Centrifugal

Answer: (A)

Fuel oil systems require a pump that provides a steady, metered flow at the pressures needed by the engine’s fuel delivery train. A vane-type pump does this well because it’s a positive-displacement device: sliding vanes ride in the pump housing, forming sealed chambers that trap a fixed amount of fuel. As the rotor turns, those chambers expand and contract, moving the trapped fuel from suction to discharge. This yields a steady discharge with good priming, reliable suction from tanks, and controllable pressure—exactly what’s needed to feed high-pressure injection gear and minimize flow pulsations.

Gear pumps share the positive-displacement benefit, but vane pumps are often preferred in fuel-oil service for smoother flow and easier priming. Diaphragm pumps are typically used for leak-tight transfer or handling fluids with special requirements and aren’t the standard choice for continuous engine fuel supply. Centrifugal pumps, while good for high-volume, low-pressure applications, don’t provide the metering and pressure control needed for precise fuel delivery to injectors.