Leakage in the Fuel pipeline may cause the Fuel Pump to burn out through two mechanisms: insufficient flow causing overheating and electrical short circuit. According to the SAE J1681 standard, fuel pumps rely on fuel flow for cooling (heat dissipation power ≥ 25 W). If leakage causes the flow rate to be lower than 50% of the nominal value (for example, the original factory design of 120 L/h is reduced to 60 L/h), Motor winding temperature from 85 ° C soared to 145 ° C (125 ° C over class H insulation limit), life plunged from 10000 hours to 500 hours. In 2022, Ford recalled 189,000 vehicles of the F-150 model due to leakage of Fuel pipe joints. Statistics show that 34% of the Fuel pumps failed due to overheating and carbonization, and the replacement cost of a single unit reached 2,800 yuan.
The flow attenuation caused by leakage will trigger the overload of the Fuel Pump. For example, when the pipeline leakage of the fuel system of the Volkswagen EA888 engine reaches 0.5 L/min, the pump body needs to increase the flow rate by 30% (from 150 L/h to 195 L/h) to maintain a pressure of 4.0 bar. Lead to current from 8 a to 12 a (super) rating of 50%, brush wear rate speed up 400%. Laboratory data shows that continuous overload operation for 15 minutes can reduce the thickness of carbon brushes from 5 mm to 2 mm (shortening their lifespan by 70%), accompanied by a sharp increase in the spark rate from 5 times per minute to 120 times per minute, and the probability of causing motor short circuits increases by 9 times.
Excessive concentration of fuel vapor is another risk. When the leakage point is less than 30 cm away from the Fuel Pump, the vapor concentration can reach the lower explosive limit (1.4% volume concentration) within 5 minutes. If the electric spark of the pump body (energy ≥ 0.02 mJ) ignites, the flame propagation speed can reach 300 m/s. Statistics from the NFPA in the United States show that 12% of vehicle fires are related to Fuel system leaks, among which 27% of the cases led to the burnout of the Fuel Pump circuit board (with a median total repair cost of $18,000). For instance, in 2021, the Tesla Model S suffered a direct loss of over 50,000 US dollars due to a loose and leaking fuel pipe clamp after sale, which caused a short circuit and fire in the pump body below the battery compartment.
Electrical corrosion aggravates the malfunction. After the leakage of ethanol Fuel (E10), the moisture absorption rate can reach 0.5% moisture per day. Electrolyte (with an electrical conductivity of 0.1 S/m) is formed at the Fuel Pump plug, resulting in a 6-fold increase in the terminal corrosion rate (the amount of patellar formation increases from 0.02 g/ month to 0.12 g/ month). BMW technical bulletin shows that such corrosion will make the contact resistance Ω from 0.1 to 2.5 Ω, cause local temperature of 80 ° C, burned plug probability of 63% (5% probability of original design).
Economic analysis indicates that the average cost of repairing the leaking pipeline is only 500- 1,500 yuan (including labor costs), but ignoring the chain losses such as the replacement of Fuel Pump (2,000-6,000 yuan), wiring harness assembly (3,000 yuan +), and post-fire handling (50,000 yuan +) caused by the leakage, The comprehensive maintenance cost can reach 20 to 50 times that of preventive maintenance. For instance, a certain user delayed the repair of the slight leakage in the fuel pipe of the Subaru WRX (with a leakage rate of 0.1 L/h). Six months later, the ECU was burned out due to overheating of the pump body, and the total repair bill reached 32,000 yuan.
Compliance solutions include:
The temperature of the Fuel Pump housing is detected using an infrared thermal imager (such as FLIR T540). If it exceeds 90°C, the machine needs to be stopped immediately.
Fuel system pressure test (standard 6 bar pressure held for 5 minutes, leakage ≤ 1 mL/min);
Replace the fuel pipe that complies with the SAE J30R9 standard (with an ethanol corrosion resistance life of ≥ 10 years). Industry data confirm that regular inspection (every 2 years / 40,000 kilometers) can reduce the failure rate of Fuel Pump caused by leakage from 18% to 2.3%, and save 82% of the comprehensive holding cost.