The influence of high-altitude condition on Fuel Pump performance is mostly expressed in the change in fuel pressure and flow rate caused by the decrease in air density. According to the SAE J1349 standard, with each 1,000 meters’ increase in altitude, atmospheric pressure decreases by approximately 11.5%, forcing the Fuel Pump’s output pressure to increase by 8%-12% in order to provide a constant air-fuel ratio. For instance, testing of the Toyota Hilux in the Qinghai-Tibet Plateau (4,500 meters high) showed that the Fuel pressure of the original Fuel Pump dropped from 3.8 Bar to 3.1 Bar, and the flow fluctuation became as much as ±15%, weakening the engine power by 19%. But modified high-pressure pumps (e.g., the Bosch HDP 5 series) were replaced by modifying the pressure valve, The output was regulated to be 4.2±0.2 Bar, and the power recovery efficiency was 93%.
Low-temperature and low-oxygen environments increase the challenge in fuel atomization. The 2022 test data on mining trucks in the Chilean Andes Mountains show that at temperatures of -25℃ and altitudes of 3,800 meters, the Fuel atomization particles diameter of the common Fuel Pump increases to 45 microns (22 microns in the plane area), and the combustion rate decreases from 86% to 64%. To counter this problem, Delphi has launched the high-altitude optimized Fuel Pump integrated heating module, which can heat the fuel temperature from -30℃ to 20℃ in just 90 seconds, optimize the atomization particles to 18 microns, and enhance the cold start success rate to 98%. Also, the hypoxic environment (oxygen concentration of 14.5%) causes the ECU to increase the Fuel injection pulse width by 12%. If the maximum of the Fuel Pump flow rate is low (e.g., below 5 liters per minute), it may cause fuel supply interruption. Statistics from J.D. Power show that such faults account for 37% of break-down cases at high altitudes.
The fuel type’s compatibility with the pump body material is equally crucial. A study by China National Petroleum Corporation in 2023 reported that the application of E10 ethanol gasoline in areas above 3,000 meters in elevation increases the corrosion of Fuel pump impellers 2.3 times compared to regular areas. The main reason is that low air pressure accelerates ethanol evaporation (the evaporation loss rate is increased by 18%), and the residual moisture concentration reaches 0.8%, improving the metal part rusting. For Walbro 450LPH fuel pumps with ceramic-coated impellers, in the same conditions, wear is only 14% less than with regular stainless steel impellers, and their service life increases to 120,000 kilometers. The smart Fuel Pump of Tesla Cybertruck, by means of the altitude – fuel viscosity adaptive algorithm, during the test at 5,000 meters altitude in Peru, the fuel flow fluctuation rate was compressed from ±12% to ±3%, and the energy consumption efficiency was increased by 22%.
Industry cases confirm the high-altitude optimization necessity. Statistics for the 2021 Dakar Rally report that 63% of the race cars’ Fuel Pump failures occurred in the areas of over 2,000 meters in altitude, of which Vapor locks accounted for 41%. The team’s rate of completion increased from 72% to 89% after the upgrade of the two-stage turbo pump (e.g., Aeromotive Stealth 340), which indeed resolved the low-pressure state by increasing the fuel flow rate (4.5 liters per minute to 6.8 liters per minute) and preventing bubble formation (bubble volume from 5% to 0.8%). According to the Frost & Sullivan report, high-altitude dedicated Fuel pumps’ market size around the world will be 940 million US dollars in 2025, among which pressure compensation and material innovation technology promote more than 65% growth rate.