Current overload of the Fuel Pump is usually caused by mechanical resistance or electrical faults. For example, according to the test data of SAE International, when the wear of the fuel pump motor bearing exceeds 0.2 millimeters, the rotational resistance moment increases by 35%, resulting in the working current rising from the standard value of 5A to 8A, the power loss increasing by 60%, and at the same time, the winding temperature soaring from 70°C to 110°C. Take the recall of the Ford Escape in 2021 as an example. Due to the deformation of the fuel pump impeller (with a tolerance exceeding ±0.15 millimeters), the peak current reached 12A (140% higher than the design value), causing the fuse melting rate to increase by 27%. The cost of a single repair was approximately 400 to 600 US dollars.
The blockage of the fuel system is another key factor. Bosch’s technical report shows that when the fuel filter is clogged (pressure difference > 50 kPa), the fuel pump needs to increase the output pressure to more than 6 bar (exceeding the rated value by 20%), the motor load current increases from 4.5A to 7.2A, and the wear rate of the brush increases by three times. Statistics from a certain auto repair chain brand show that when using fuel with ethanol content > 15%, the accumulation rate of deposits inside the fuel pump increases by 40%, the friction coefficient between the plunger and the cylinder block rises from 0.08 to 0.15, the current fluctuation range expands to ±1.5A (the normal value is ±0.3A), and the average service life shortens to 40,000 kilometers (the designed service life is 80,000 kilometers). In addition, a malfunction of the negative pressure valve of the fuel tank (vacuum degree < -5 kPa) can cause the cavitation probability of the fuel pump to increase from 3% to 18%. When the impeller idles, the instantaneous peak current can reach 10A, triggering the overload and burnout of the control module.
Circuit design flaws may also lead to abnormal currents. In the software update of Tesla Model Y in 2022, the PWM control logic error of the Fuel Pump was fixed. This defect expanded the duty cycle fluctuation range from 75%-85% to 60%-95%, increased the average current of the motor from 5.8A to 7.4A, and the energy efficiency decreased by 19%. Similarly, Delphi’s experiments show that a 0.5Ω increase in the impedance of the fuel pump wiring harness (such as oxidized joints or insufficient wire diameter) will cause the voltage drop of the 12V power supply system to increase from 0.3V to 1.2V. To maintain power output, the current needs to be increased from 5A to 6.8A, and the temperature rise of the cable reaches 45°C (20% above the safety standard). Industry cases show that installing non-original fuel pumps (such as reducing the number of turns in the motor windings of some third-party products by 15%) will cause the no-load current to rise from 1.2A to 2.5A, and the heat generated by the armature will increase by 110%.
Maintenance and technological innovation can effectively control abnormal current. According to the data from the American Automobile Association (AAA), regularly replacing the fuel filter (every 30,000 kilometers) can reduce the probability of fuel pump current exceeding the limit from 32% to 9%, and at the same time restore the fuel flow to the designed value (such as 80 L/h±5% for a certain Bosch model). The low-friction ceramic bearings (with a friction coefficient of 0.02) developed by Schaeffler Group can reduce the operating current of fuel pumps by 18%, but the cost increases by approximately 25%. Market analysis agency Frost & Sullivan pointed out that the penetration rate of intelligent fuel pumps (integrated current monitoring chips) has reached 18% in 2023. By adjusting the PWM frequency in real time (ranging from 1 to 10 kHz), it has compressed the standard deviation of current fluctuations from 0.8A to 0.2A, and the accuracy rate of fault diagnosis has increased to 95%. For example, the intelligent fuel pump equipped in the Audi e-tron GT automatically triggers the frequency reduction mode when the current exceeds the limit by 10%, avoiding overload damage to the electronic control unit (ECU) and reducing the maintenance cost by 40%.