Instable voltage is the most critical cause of Fuel Pump burnout. Test data show that when the supply voltage is less than 11V (normal 13.5V±0.5V), the motor current of the pump body grows from 5A to 9A (80% overloaded), and the winding temperature rises to 160℃ within 15 minutes (in normal working status ≤85℃). The maintenance case of Ford F-150 shows that the growth in resistance is due to corrosion of the circuit to 0.8Ω (normal≤0.1Ω), the annual average replacement times of the pump body are up to 2.3 times, and the failure rate is lowered to 0.2 times/year after cleaning the wiring harness. SAE J2340 standard highlights that voltage fluctuation > ±10% will triple the wear rate of the brush, and the incidence of short circuit due to carbon powder accumulation will rise to 67%.
Fuel contamination hastens components’ wear. If the filter is not timely replaced (> 60,000 kilometers), the Fuel Pump must contend with an additional back pressure of > 0.8Bar (usual 0.3Bar), and the impeller shaft has an additional loading of 42%. Upon disassembly of the Volkswagen EA888 engine, it is seen that with the clogging degree of the filter screen being 85%, the running temperature of the pump body rises from 75℃ to 105℃ and the service life of the ceramic bearing falls from 150,000 kilometers to 40,000 kilometers (by 73%). A survey of consumers of ethanol gasoline in Brazil shows that the corrosion of the copper armature is five times higher when water content in E100 fuel is above 0.4%, and the burnout cycle reduces from 100,000 kilometers to 23,000 kilometers.
Burnout fails as soon as there is a failure in thermal management. If the Fuel tank is in a state of less than 1/4 oil level for a long time, the immersion depth of the Fuel Pump is improper. The test analysis says that if the oil level is lowered 5cm below the pump body surface level, the efficiency in heat dissipation drops by 58% and the temperature rises up to 120℃ (safety limit 95℃) after 1-hour continuous run. Statistics of BMW N55 engine show that at running at low oil level in hot operating condition (40℃), the MTBF (Mean Time between Failures) of pump body reduced significantly from 120,000 kilometers to 38,000 kilometers. Utilization of a fuel cooling circuit (e.g., in Audi S-Tronic) can reduce the return oil temperature from 95℃ to 55℃, and can double the service life of the pump body to 180,000 kilometers.
Design defects and parts wear led to the third-party Fuel Pump impeller dynamic balance error > 15g·mm (original factory ≤5g·mm), which caused 1200Hz high-frequency vibration and raised the bearing impact load to 230N (norm 80N). Statistics from Toyota Camry indicate that the rate of abnormal noise for non-original pump bodies at 30,000 kilometers is 78%, while that of original products is just 12%. Bosch’s technical report indicated that the nylon impeller of the particular contract pump body increased by 0.8% in E20 ethanol gasoline, and the impeller generated heat due to friction from the pump casing, and the chance of burnout increased to 89%.
The overload condition exceeded the design limit. For the car modified, the power increased by 30%, the fuel flow demand of the Fuel Pump increased from 80L/h to 110L/h. But due to the absence of the simultaneous upgrading, there was still the continuous overload operation of the motor. The Subaru WRX STI example shows that in the example of the 500hp tuned vehicle with the stock factory pump, the oil pressure at the full throttle condition drops from 4.0Bar to 2.3Bar (-43%), the highest armature temperature is 180℃, and it needs to be replaced with an average interval of 3 months. After the retrofit to a dual-pump configuration (such as the Radium dual-oil pump bracket), redundancy in flow is 40%, and risk of burnout is reduced to zero.
System mismatch faults resulted in a series of faults. In turbocharged versions, a naturally aspirated Fuel Pump was fitted incorrectly (pressure difference tolerance 3.0Bar vs actual requirement 5.0Bar), and plunger seal rupture overpressure leakage rate increased to 2ml/min (specification ≤0.1ml/min). The actual test of the Mercedes-Benz M276 engine shows that such improper installation will cause the fuel to dilute the engine oil (concentration > 5%), increase the explosion pressure of the crankcase by 0.3Bar, and ultimately cause the insulation failure of the pump body motor. After the right matching of the high-pressure pump (e.g., Denso 950-0110), the rate of disposal of correspondent faults is 100%.
These figures show that maintaining the voltage stable (13.5V±5%), replacing the filter often (every 40,000 kilometers), maintaining the oil level over half, and selecting the original factory-spec Fuel Pump can minimize the risk of burnout to below 3%. BMW fault statistics confirm that following the above measures, the proportion of pump body replacement during the warranty period reduced from 19% to 0.7%.