Under the standard operating conditions of passenger vehicles, the working noise level of the Fuel Pump (fuel pump) originally configured in the factory is usually below 40 decibels (dB(A)), which complies with the requirements of the ISO 362-1 vehicle noise regulation. For instance, the fuel pump of the eighth-generation Honda Civic generates A sound pressure level of 32-35dB(A) at idle speed, which is equivalent to the background volume in a library environment (30-40dB(A)). Technical tests show that its main vibration frequency is concentrated between 1000 and 2000Hz, and the peak amplitude is controlled within 0.03 millimeters. Moreover, modern vehicles can reduce the noise transmitted from the pump body to the vehicle body by more than 90% through rubber shock-absorbing brackets. According to Bosch’s 2021 NVH performance report, when the oil pump flow rate was maintained at the normal value of 50L/ hour, the measured values in the cabin of 96% of the models were below 25dB(A) – only 60% higher than the human breathing sound (10dB(A)).
When the load conditions intensify (such as full throttle acceleration), the fuel flow demand may increase sharply by 300%, and at this time, the noise level increases nonlinearly with the rise in pressure. The measured data shows that when the output pressure of the oil pump increases from 3bar to 6bar, the noise level will jump from 38dB(A) to 52dB(A), with an increase rate of 37%. The main noise sources are the high-frequency turbulence of the impeller (frequency 4000-6000Hz) and the commutation vibration of the motor (component 200-400Hz). The fuel pump noise test of the Porsche 911 (992) in track mode shows that: When the pressure exceeds 7bar, the noise reaches A peak of 59dB(A), but it is still 15.7% lower than the tire road noise (70dB(A)). This is attributed to its three-stage hydraulic pulsation damper, which suppresses the pressure fluctuation within ±0.2bar (±1.0bar for ordinary pumps), and the noise increment optimization rate is 65%.
Abnormal noises often point to the risk of equipment failure. The German TUV certification standard stipulates that when the operating noise of the Fuel Pump exceeds the reference value by 10dB(A) or low-frequency harmonics below 200Hz persist (usually < 50Hz), it indicates that the probability of mechanical failure exceeds 80%. The empirical case is the General Motors recall incident in 2020: Due to the tolerance of the fuel pump gear set exceeding 0.05 millimeters, the idle abnormal noise reached 48dB(A) (the upper limit of the standard value is 42dB(A)). Subsequent statistics show that the damage rate of this batch of pump bodies reached 38% after driving 60,000 kilometers. The SAE J1497 test procedure in the United States emphasizes that if the sound pressure level in the 2500Hz frequency band suddenly increases by 15dB, it often indicates that the bearing wear exceeds the safety threshold (radial clearance > 0.1mm).
The oil pumps of commercial heavy vehicles are confronted with more severe acoustic environments. The nominal noise of the high-pressure common rail pump of the Volvo FH16 truck is 68dB(A) (flow rate 150L/ minute), which is close to the normal conversation volume (60-70dB(A)). However, its use of an integral cast aluminum alloy shell reduces the vibration conduction rate in the 300Hz frequency band by 40%, and the noise beside the driver’s ear is controlled below 55dB(A). An extreme case was the 2023 Dakar Rally car – to cope with A fuel throughput of 120 liters per minute, the noise from the fuel pump was as high as 81dB(A), but with the carbon fiber sound insulation cover wrapped around it, the actual perceived increase inside the car was only 4dB(A).
Innovative materials are reshaping industry benchmarks. The electric fuel pump of Toyota’s latest hydrogen fuel cell vehicle, Mirai, adopts ceramic rotor and magnetic levitation bearing technology, reducing the operating noise to 26dB(A), which is 48% lower than that of traditional pumps. This technology attenuates the high-frequency components above 2000Hz by 99%, and the noise increase within its life cycle is less than 1dB/ 10,000 kilometers. Quantitative data shows that for every 1dB reduction in fuel pump noise, the development cost of the vehicle’s NVH needs to increase by approximately 5%, but the improvement rate of customer satisfaction can reach 2.1% (J.D. Power 2022 survey), verifying the key value of acoustic optimization for the consumer experience.