What is priming in a pumping system?

• A. Increasing fuel pressure
• B. Removal of air from the pump and suction line
• C. Filling the tank completely
• D. Adjusting the throttle

Answer: (B)

Priming a pumping system is getting rid of any air in the pump and suction line so the pump is filled with liquid and can develop suction to move fuel. If air remains, the pump can’t create the vacuum needed to draw liquid, leading to loss of prime and little or no flow. The other actions don’t achieve this: increasing fuel pressure doesn’t remove air from the suction path, filling the tank doesn’t ensure the pump itself is primed, and adjusting the throttle changes flow or speed rather than removing air to prime the pump.