Fuel pumps normally buzz due to problems in the flow of fuel, pressure, and sometimes mismatched parts inside that raise friction or stress. The common ones include low fuel pressure, during which the fuel pump has to stress more and produce a buzzing sound. Because, if the pressure falls below the desired pressure, then the pump needs to cycle more rapidly for maintaining the level of fuel delivery, which increases the noise. The low pressure in operation allows the loss in efficiency for a given fuel pump to go up to 15%, which in return reflects badly on the general performance of a vehicle.
The buzzing might also be a result of the fuel lines that are clogged or restricted. Partial blockages can take place because of debris or contaminants in the fuel system. Due to these blockages, with time, the pump faces resistance and hence produces noises of buzzing when the Fuel Pump has to work against this extra strain. It has been said that nearly 20% of all premature failures in reference to the Fuel Pump are caused by fuel line blockages; this in return increases stress, which expedites wear on the motor and other internal parts of the pump.
Most of the time, the reason for the buzzing could also be related to an issue with the electrical system, like unstable power or the wear and tear of the relay. When the electrical current fluctuates, that means the pump doesn't have consistent power flow and thus will run irregularly to give those buzzing sounds. Make sure to check the electrical connections for stability, as uneven power flow can cut up to 10% of the pump's life over time.
Other main causes of a humming Fuel Pump are low fuel levels. The fuel in the tank cools the pump, therefore a low level of fuel will result in overheating of the pump, which makes it to hum or whine. The repeated running of a vehicle with less than one-quarter of a tank will result in the repeated overheating of it with higher wear, which would decrease the efficiency by some 5-10% per year.
The early detection of the causes for buzzing noise will help in taking remedial actions before this turns out to be a costly replacement. So, professionals advise periodic checking and maintenance of the fuel system; on doing so, one can prevent early wear of Fuel Pump and extend the life of the pump by some years, and that is the importance of early diagnosis and preventive care.