Driving with a faulty Fuel Pump will make the engine lose 30%-50% of its power. For instance, Ford recalled 650,000 F-150 vehicles in 2020 since their fuel pump impellers were cracked. Data from the United States National Highway Traffic Safety Administration (NHTSA) show that the risk of sudden stall of the affected vehicles when driving at high speeds is 4.2 times higher than that of normal vehicles. When the fuel pressure is 40% lower than the original factory set (usually 300-600 kPa), the air-fuel mixture can be deviated from the theoretical value by ±15%, causing incomplete combustion. According to SAE International studies, these conditions will cause a 120% instantaneous increase in hydrocarbon (HC) emissions in the exhaust gas. The chance of the three-way catalytic converter temperature exceeding the 950℃ threshold (typically 600-800℃) is increased by 70%, which will eventually cause the catalytic converter to be damaged and the maintenance cost to increase by 2000-3500.
The immediate risk of the Fuel Pump’s complete failure has a clear statistical basis. AAA Association of America study reveals that in the roadside rescue calls due to fuel system breakdown, 28% are caused by the fuel pump directly. Out of these, 19% of the cases occur when the vehicle’s speed exceeds 80 km/h, and the engine suddenly shuts down, resulting in a loss of steering power. The stopping distance was lengthened by 2.3 meters (IIHS crash test statistics). In one instance, an investigation into a severe traffic accident in California in 2021 discovered that the vehicle involved had driven 1,600 kilometers continuously even with the P0087 fault code (low fuel pressure) warning. Eventually, the fuel pump motor was overloaded and burned out. The ECU record showed that the fuel pressure dropped to 85 kPa (only 18% of the standard value) five minutes before the failure.
Economic cost calculation indicates that deferred maintenance may cause collateral damage. As per the Bosch Automotive After-sales 2023 report, the initial replacement cost of the Fuel Pump fault is approximately 400-800. If it causes synchronous damage to the high-pressure fuel pump with a probability of 37%, then the total cost of maintenance will rise to 1500-2800. More seriously is that long-term low-pressure fuel supply will triple the carbon deposit rate of fuel injectors. According to the test data of Delphi Technologies, when the fuel pressure is below 200 kPa for 200 hours, the flow deviation of fuel injectors will exceed ±12%, and they need to be cleaned or replaced at 600−1200.
From the legal risk point of view, there are some states in the United States that have laws which dictate that if the driver is aware that the fuel system has failed and still drives and, as a result, causes an accident, the vehicle owner will be 75% to 100% liable. In a 2019 Michigan court case, a driver had to pay $235,000 in damages for a chain of rear-end collisions caused by an abnormal noise from a fuel pump (typically 78dB, 35% over the factory standard) that was not repaired. The use of preventive diagnostic tools can reduce hazards. OBD-II data shows that when the Duty Cycle of the fuel pump is continuously above 90% for 10 minutes (usually 60-75%), or when the fuel flow sensor value fluctuates by more than ±20%, The system failure probability is 68% (based on the statistical analysis of 500,000 sets of fault codes by CarMD).
The manufacturer’s technical bulletin points out safety limits. For instance, Volkswagen TSB 23-06 specifies that when fuel delivery from the fuel pump is less than 70% of nominal (120L/h), the EA888 engine may activate emergency fuel cut-off protection during sudden acceleration. Empirical tests show that under the aforementioned working conditions, the duration required for slowing down the vehicle from 100 km/h to 60 km/h increases by 2.8 seconds, and the risk of lane changing and overtaking accidents increases by 41% (empirical test findings of ADAC German Automobile Club on roads). The economic comparison of regular maintenance shows that replacing the Fuel filter every 80,000 kilometers (at a cost of 50-100) can extend the lifespan of the Fuel Pump to 150,000 kilometers and reduce the failure rate by 57% compared to the non-maintenance cohort (J.D. Power 2022 Vehicle Reliability Study Report).