A low pressure Fuel Pump not only results in substantial degradation in vehicle performance and safety but also reduces its overall life. According to the SAE J2719 specification, when the fuel pump flow rate declines to less than 70% of the original design value (e.g., the original factory fuel pump flow rate of 300 L/h drops to 210 L/h), the engine power will be decreased by 15%-20%, and the 0-to-100 km/h acceleration time will be increased by 1.5-2.3 seconds. North American Highway Safety Administration (NHTSA) data in 2023 indicate that mid-road stalling crashes caused by Fuel Pump failures accounted for 3.7% of all traffic crashes throughout the year. Of these, 82% were instances with a fuel pressure level below 2.5 bar (normal operation would be between 3.0-4.5 bar), and the median maintenance cost was $680.
Insufficient fuel supply can cause a chain of malfunctions. When the Fuel Pump pressure fluctuation is outside ±1.0 bar, the ECU air-fuel ratio control error expands from ±0.3 to ±1.8, sending the three-way catalytic converter’s temperature soaring from its usual 800°C to 1100°C and cutting its lifespan by 60%. For instance, the 2022 owner survey of Honda Civic car owners indicated that in vehicles where the faulty Fuel pumps were run continuously, the rate of catalytic converter replacement increased from the average of 1.2% per year to 9.7%, and the unit maintenance cost rose up to $2,200, 3.2 times the cost of Fuel Pump replacement.
The fuel economy deterioration is the final consequence. Degrading the Fuel Pump increases the fuel injection atomization particle diameter from 20 μm to 50 μm, decreasing combustion efficiency by 12%-18%. According to a study in Automotive Engineering in 2024, if the fuel pressure reduces from 4.0 bar to 2.8 bar, fuel consumption of a 1.5T engine per 100 kilometers rises from 6.3 L to 7.8 L (23.8% increase). Computed at the driving distance per year of 15,000 kilometers, car owners will incur another fuel cost of approximately 480 US dollars.
There are increased risks emerging with severe operating conditions. When the Fuel Pump flow rate is below 150 L/h, the turbocharged engine knocking possibility in the event of working at high rotation speed (≥5000 rpm) increases from 2% up to 28%. The 2023 German ADAC road test found that the Volkswagen Golf GTI with its low Fuel Pump underwent an engine misfire rate of 12 occurrences per minute on steady climbing conditions, and the peak exhaust temperature was over 950°C (above the ECU protective threshold), triggering the forced power reduction mode.
There are strict limits to emergency driving. The technical guides of the majority of motor vehicle companies indicate that if Fuel Pump pressure is below 2.0 bar, maximum safe driving distance is not exceeding 50 kilometers (speed ≤60 km/h). For instance, the Toyota Camry fuel pump redundancy design can tolerate a minimum fuel supply at 80% performance level degradation. But prolonged operation more than 2 hours will cause the temperature of motor winding to rise to 135°C (150°C is the critical point of melting of insulation layer), and the rate of failure will increase by 400%. In case of the need for short-distance emergency, it is recommended to turn off the air conditioner load and other loads and keep the engine speed less than 3000 rpm. This can add 30 to 50 hours to the life of the fuel pump, but you will still have to bear the risk of catalytic converter destruction (probability 62%).