What are the symptoms of a faulty hand fuel pump?

[Declan]

The most direct symptom of a faulty hand fuel pump is the engine failing to start. The hand fuel pump has two fuel supply points: one is manually operated by pressing the pump, and the other is powered by the engine's high-pressure pump. If the manual pump alone fails to deliver fuel, it doesn't necessarily mean the engine won't start. However, if the hand fuel pump is damaged and there is air in the fuel lines that requires the hand pump to prime the system, it will result in a failure to start. The hand fuel pump is responsible for pumping fuel from the tank into the fuel lines. The correct method for using the hand fuel pump is as follows: 1. Open the fuel tank. 2. Remove air from the low-pressure fuel lines: Loosen the return bolt at the top, then press the black plunger up and down to expel the air. 3. Air in the high-pressure fuel lines can be automatically removed by cranking the starter motor. Do not loosen the pipe connection nuts at the pump end, rail end, or injector end.