The performance deterioration of High RPM Fuel Pump can be measured quantitatively by such parameters as fuel pressure, flow rate and combustion efficiency. Taking the Volkswagen EA888 Gen3 engine as an example again, with the rotational speed up to 6000 RPM, the original Fuel Pump needs to guarantee the fuel pressure at 4.8 Bar and the flow rate at 8.5 liters per minute. If the pressure fluctuation is greater than ±0.5 Bar (normal is ±0.2 Bar), then the air-fuel ratio imbalance will be greater than ±0.8. The outcome is a power loss of 12%. In the 2023 Nurburgring 24 Hours Endurance race, one of the teams had a sudden drop in the flow rate of the third-party Fuel Pump to 6.2 liters per minute at 5500 RPM, which raised the cylinder misfire rate to 17% and lost 3.2 seconds in lap time.
Impeller wear and motor load are common bottlenecks. The experiments on the Honda K20C1 engine show that when Fuel Pump impeller clearance is more than 0.08mm (original factory specification ≤ 0.03mm), the flow weakening rate at high rotation speed (7000 RPM) is as high as 23%, and the fuel pressure drops from 5.0 Bar to 3.9 Bar. The ECU must close the throttle opening by 15% to protect the engine. Car and Driver”‘s test data in America show that after 100,000 kilometers of use, the highest temperature of the motor of the Fuel Pump is 148℃ at 6500 RPM (92℃ for the new pump), the winding resistance increases by 0.3Ω, and the electric power efficiency drops from 87% to 71%. Fuel injection pulse width compensation needs to be increased by 22% in order to maintain power output.
Fuel temperature has significant influence on system design. When BMW S58 engine is in track mode and still running at high speed (6200-7200 RPM) for 10 minutes, the Fuel rail temperature rises from 45℃ to 78℃. When the Fuel Pump is not well heat-dissipated (for example, no cooling return valve), the flow fluctuation rises to ±18%. The Porsche 911 GT3 incorporates a two-stage Fuel Pump (main pump flow rate 7.2 liters/minute + booster pump 3.8 liters/minute) with pressure stability of ±0.1 Bar at 8500 RPM. But the single-pump adjustment to change the pressure deviation is more than ±0.9 Bar, and the detonation sensor trigger frequency is 6 per revolution. The peak pressure in the cylinder has decreased by 11%.
Data should substantiate diagnosis and optimization strategies. If the Fuel correction value (LTFT) measured by OBD exceeds ±10% (normal ±5%) in the high-speed range, or the short-term fuel correction (STFT) frequently exceeds ±15%, it can indicate irregular fuel supply from the Fuel Pump. The case of the Ford Mustang GT owner shows that after fitting the Bosch 044 high-pressure Fuel Pump, the fuel flow at 7000 RPM increased from 7.1 liters per minute to 9.3 liters per minute, air-fuel ratio variation narrowed to ±0.3, and the 0 to 100 km/h acceleration time decreased by 0.4 seconds. SAE studies have discovered that the use of silicon carbide-coated impellers can reduce the wear rate at high speed by 64%, extend the maintenance cycle from 80,000 kilometers to 150,000 kilometers, and reduce the average annual power attenuation cost by 2,100 yuan.