A buzzing noise from the fuel pump will typically mean that there is enhanced stress on the system and could be due to a combination of one or more of several factors, which most require urgent attention. The most common reason for a noise was attributed to a clogged fuel filter. As soon as a fuel filter reaches a blocked condition, somewhere after 20,000 to 30,000 miles, the pump needs to work harder to push fuel through it, making more noise. This is because the pump motor puts in extra effort when working under extra load, thus causing the buzzing. It strains, hence, reduces its efficiency and lifespan by about 10-15%.
The other very common cause of a buzzing fuel pump is running low fuel in the tank. Fuel pumps use gasoline to cool and lubricate the pump; therefore, operating a vehicle with less than a quarter of a tank on a regular basis can cause increased heat and wear. The excessive heat is produced by insufficient fuel flow that raises the pump's internal temperature beyond the optimal 140°F, overworking the motor and producing a specific buzzing noise. A higher rate than a quarter full of the tank averts this problem and prolongs pump life.
Other causes of buzzing include electrical problems, such as poor connections or low voltage. All fuel pumps operate on approximately 12 volts, and when this goes down to 10 volts or less, due to bad wiring or a weak battery, then one can certainly expect erratic performance and added noise. Testing the battery and inspecting wiring connections help identify and resolve voltage-related buzzing, which also has an impact on the pump's fuel flow rate of up to 10-20%.
Too much buzzing may also mean that the fuel pump relay is failing. It works by regulating the amount of electrical current going to the pump, ensuring a smooth electric flow. A bad relay can easily make the pump shut on and off quickly, producing a buzzing sound. A typical replacement cost for such a relay will fall in the range of $20 to $50, while the proper replacement will immediately stop the noise and prevent further damage to the fuel pump.
Buzzing, in some high-performance or modified vehicles, can mean that the fuel pump installed in your vehicle is too small for the requirements of your engine. Engines requiring over 300 liters per hour will strain a conventional fuel pump, which may be excessively noisy and wear. Installation of a high-flow Fuel Pump rated for your vehicle application will not only eliminate buzzing but also provide adequate fuel delivery for both performance and service life.
By identifying these causes and correcting them, the buzzing fuel pump will be eliminated along with protection to the system from wear and further possible failure of components. Thus, operations will be smoother and more efficient.