Unstable voltage can indeed lead to progressive damage or even sudden failures of the Fuel Pump, mainly due to abnormal operation and increased load caused by insufficient power supply. According to the specifications of the automotive electrical system, the DC motor of the fuel pump needs to operate stably within the nominal voltage range of 12V±10% (i.e., 10.8V to 13.2V). However, actual vehicle test data shows that when the ignition system is started or high-power equipment is working (such as the air conditioning compressor), the circuit voltage drop may reach a peak of 8.5V (transient lasting for 0.5 seconds). At this point, the motor speed drops by more than 15%, causing the fuel flow to sharply decrease to less than 75% of the rated value, directly triggering the engine insufficient fuel supply fault code (such as P0230). In 2019, the Bosch Powertrain Laboratory conducted a study simulating repeated low-voltage impulse tests: after applying voltage perturbations of 20 times a day, with a amplitude of 9V and a duration of 2 seconds to 300 fuel pumps of the same model, 38% of the samples experienced winding overheating or brush damage within a 500-hour accelerated aging cycle, with the failure rate increasing by 22 percentage points compared to normal operating conditions.
There is a clear quantitative correlation between voltage drops and the wear of fuel pump carbon brushes and commutators. The Society of Automotive Engineers (SAE) analysis of the motor durability report of a certain OEM supplier shows that if the motor operates for a long time at a voltage lower than 11V (typical conditions include wire corrosion in old vehicles or connector resistance exceeding 0.5Ω), the brush current density will sharply increase by 12-18A due to the demand for torque compensation (about 6-8A under normal load). This led to the brush wear rate accelerating from an average of 0.15mm/1000 hours to 0.28mm/1000 hours, and the estimated life cycle shortening from the designed 150,000 kilometers to less than 90,000 kilometers. In 2021, General Motors’ investigation report on the class-action lawsuit filed by Chevrolet Malibu owners admitted that a ground voltage loss of over 1.7V was one of the core factors causing the fuel pump to fail prematurely (on average at 63,000 kilometers), and it would cost 400 to 600 yuan to replace the entire assembly.
The secondary effects caused by voltage fluctuations also significantly shorten the functional life of fuel pumps. Delphi’s technical notice reveals that when the fluctuation range of the input voltage of the fuel pump exceeds ±1.5V (frequency > 5Hz), the response accuracy deviation of the built-in pressure regulating valve increases to ±12% (the standard requirement is ±5%), forcing the fuel pump to frequently overpressure compensate, and the driving current of the related solenoid valve increases by 30%-40%. This dynamic imbalance causes the oil pump to operate in a high-temperature range above 60°C for a long time (15-20°C higher than the normal temperature state). According to the Arrhenius acceleration model, the failure rate of electronic components doubles for every 10°C increase in temperature. Among the 10,000 fuel system failures recorded by the Australian Automobile Association in 2017, 13.2% had battery terminal voltage lower than 11.4V or unstable generator output (fluctuation coefficient CV > 0.07).
To prevent voltage interference, power parameters should be systematically monitored. If the voltage drop of the oil pump relay contact captured by the oscilloscope is greater than 0.3V or the power line loss is greater than 0.8V, the line needs to be repaired (SAE J1349 standard). It is recommended to upgrade the cross-sectional area of the replaced cable from the original 18AWG to 16AWG to reduce the resistance by 40%. Consumer complaints received by the US Federal Trade Commission show that vehicles equipped with inferior inverters (ripple > 150mV RMS) or audio power amplifiers (> 800W) have a fuel pump failure claim rate that is 19.7% higher than the original factory circuit configuration. Real-time diagnosis suggests that when the fluctuation range of the oil Pump power supply voltage exceeds ±0.5V at idle speed or is lower than 9.5V during cold start transient, the power system should be immediately repaired to avoid irreversible damage to the Fuel Pump caused by abnormal power supply.