Voltage drop has a direct and significant negative impact on the performance of the Fuel Pump. According to the SAE J1539 standard, when the system voltage is lower than the designed working value (usually 13.5V±10%), the rotational speed of the pump will show a nonlinear decrease. Experimental data show that for every 1V reduction in voltage, the flow output of the electric fuel pump decreases by an average of 15%±2%, while the power consumption drops by 18%, resulting in a 40% increase in the risk of insufficient fuel supply under high load demands of the engine. A typical case is the recall incident of a certain OEM manufacturer in North America in 2017. Due to the excessive resistance of the wiring harness, the average voltage dropped to 11V, resulting in a fuel pump flow loss rate as high as 28% for the related models. The probability of triggering fault code P0087 (low fuel rail pressure) increased threefold.
The key performance parameters are significantly affected by voltage fluctuations, and the pressure output is directly proportional to the square of the voltage. For example, for a fuel pump with a design pressure of 60psi, when the voltage drops to 12V (a decrease of approximately 12%), the measured pressure output drops to approximately 50psi, with a deviation of 16.7%, far exceeding the 5% tolerance range stipulated in the ISO 16750-2 standard. The decrease in rotational speed simultaneously intensifies cavitation. Bosch engineering research shows that a 10% reduction in voltage can increase the probability of cavitation inside the pump by 25%, accelerate the erosion of the impeller, and shorten the service life to less than 70% of the original design life of 120,000 kilometers. As a result, the maintenance cost increases by an average of $300±50 per year.
Voltage instability can also cause chain system failures. When the voltage drops to the critical threshold (such as below 9V), the flow output of the fuel pump may drop sharply by more than 60%, causing a deviation of ±0.5λ in the mixture concentration, resulting in a decrease of 8%-12% in combustion efficiency and an increase of approximately 6% in fuel consumption. The actual case is derived from the accident investigation report of the Australian Transport Safety Authority (ATSB) in 2021: Due to the aging of the battery in a certain truck fleet, the voltage fluctuated periodically (from a peak of 14.2V to a trough of 10.8V), causing the temperature rise of the fuel pump motor winding to exceed the standard (up to 130°C). The failure rate increased by four times compared to normal working conditions. On average, it needed to be replaced 1.8 times every 100,000 kilometers, which was much higher than the industry average of 0.4 times.
The solution involves system-level voltage stability guarantee. The technical specification requires that the voltage drop of the circuit does not exceed 0.5V (in accordance with the SAE J1128 standard), and the wire diameter selection needs to match the current load (for example, a 10A load requires 16AWG wire). Measured data prove that installing relays for direct power supply can reduce line loss by 75%, keep the voltage above 13V, and increase the stability of flow output to 98%±1%. The successful case can be seen from Chevrolet’s upgrade plan for the Silverado model in 2023: By optimizing the power supply path to control the voltage drop within 0.3V, the peak flow rate of the fuel pump increased from 260L/h to the designed value of 290L/h, the engine power recovery rate reached 100%, and at the same time, the MTBF (Mean Time Between Failures) was extended to 150,000 miles, achieving a 22% reduction in the total life cycle cost.