The core manifestation of vapor resistance in a fuel pump is the vaporization of fuel in the fuel line, which forms a gas lock and is directly manifested as a sudden drop in flow and pressure fluctuations. When the ambient temperature is above 40°C, the vapor pressure of ordinary gasoline rises to 48kPa. If the net positive suction head (NPSHr) at the pump inlet is lower than the 1.5m liquid column, the flow rate will drop sharply from 50L/min to less than 15L/min. The measured data of taxi fleets in the Middle East in 2023 shows that the failure rate of hot shutdowns and restarts of unmodified vehicles is as high as 34%, and the pointer of the oil pressure gauge fluctuates sharply within the range of 2.0 to 4.5bar (fluctuation <±0.3bar under normal conditions).
The abnormal noise spectrum is an important diagnostic basis. When cavitation occurs, the sound pressure level in the 2000-5000Hz frequency band suddenly increases by 12dB. The acceleration sensor shows that the vibration amplitude of the pump casing reaches 5.3g (the normal value is 0.8g). The technical specification of Ford SSM 50188 states that under such working conditions, the circulating shock frequency of the plunger pump will double from 120Hz to 480Hz. Data analysis from the recorders of mining trucks in Australia confirmed that the correlation between vibration energy over-limit alarms and Fuel Pump failures reached 89%.
The critical threshold of temperature determines the risk level. Ethanol gasoline (E10) has a gas-liquid volume ratio soaring to 350:1 at 45°C, resulting in a 65% decline in pump efficiency. BMW GT03027 report reveals that when the oil pipe temperature exceeds 62°C, the probability of vapor resistance reaches 72%, and the use of multi-layer heat insulation shesheath (reducing the surface temperature by 28°C) can suppress 90% of the vaporization risk. It is worth noting that the US Environmental Protection Agency requires that starting from 2025, all Fuel pump be compatible with E15 ethanol fuel, and the temperature resistance standard be raised to 80°C.
The parameter distortion of the electronic control system has predictive value. The current sensor captured the characteristic of a sudden drop in load: it dropped from 12A to 5A within 2 seconds (a decrease of 58%), and at the same time, the PWM duty cycle was forced to increase to 85% but still could not restore the pressure. The log of the thermal management system of Tesla Model 3 shows that when the coolant temperature exceeds 50°C, the trigger rate of vapor resistance warning increases by 340%. At this time, actively activating the fuel circulation cooling module (flow rate 3L/min) can bring the oil temperature back below 35°C.
Extreme cases verify the reliability of the solution. In the Sahara Desert oil transportation project, the efficiency of the common centrifugal Pump decreased by 87% at the surface temperature of 52° C. By switching to the KEMSO supercharged Fuel Pump (pressurized to 0.8bar at the inlet) in combination with the PTC oil circuit heater (maintaining the fuel temperature of 55°C±2°C), the flow rate was successfully stabilized at more than 95% of the rated value. Data from the 2022 Dakar Rally shows that the racing cars equipped with this system achieved a completion rate of 91% at an ambient temperature of 48°C (only 47% for the base pump group).
Economic benefits depend on the protection level. The basic insulation renovation (120 per vehicle) can further reduce the failure rate in urban working conditions by 90%. According to statistics from ADAC in Germany, the commercial fleet incurs a breakdown loss of €2,300 per case of traffic jam, and the investment payback period for cooling upgrades is approximately 14 months.