Low-temperature start-up delay is often caused by insufficient establishment of Fuel Pump oil pressure. Experimental data shows that at -20℃, the viscosity of regular gasoline rises to 60cP (30 times higher than at room temperature). If the output pressure of the fuel pump is lower than 280kPa (the standard requirement is 450kPa), the opening time of the fuel injector will be delayed by 1.5 seconds. The 2023 Bosch test report indicates that when the old pump starts at 0℃, the flow rate drops by 40%, resulting in only 1.8ml of fuel supply in the first 5 seconds (the demand is 4.0ml), and the probability of ignition failure increases by 50%. A typical case is the Audi Q5 recall in 2022. 100,000 vehicles had a start-up time exceeding 7 seconds (200% above the design threshold) due to insufficient pump speed in low temperatures. After replacing the high-power turbo pump, the delay was reduced to 2.8 seconds.
The low-temperature adaptability design directly determines the pump efficiency. The fuel pump with heating function can increase the temperature at the oil inlet by 15℃ through the electric heating film in an environment of -30℃, reducing the viscosity of the oil to 25cP and achieving a flow recovery rate of 85%. Tesla’s 2021 patent shows that the oil pump module integrated with PTC ceramic has a pressure establishment time of only 0.8 seconds at -18℃ (traditional pumps take 3 seconds), and the time to stabilize the voltage to 12V is shortened by 75%. The data from Hyundai Group is even more remarkable: The IONIQ5 uses an intelligent pre-heat pump in combination with low freezing point fuel, achieving a cold start success rate of 99% at -25℃, which is 40% higher than that of traditional systems.
Voltage fluctuation is another key factor. When the battery capacity decays to 300CCA, the voltage drops sharply to 9V at the moment of startup, which will reduce the oil pump speed by 50%. Actual measurements show that the resistance of an aged 300A fuse increases to 0.3Ω (0.05Ω for a new one), the power output of the oil pump decays by 35%, and the peak oil pressure only reaches 280kPa (the target value is 450kPa). According to the J.D.Power survey report, among vehicles with batteries used for more than three years, 60% of cold start delays are caused by abnormal fuel pump voltage. The solution, such as installing a capacitor module, can control the voltage fluctuation within ±0.5V and accelerate the oil pressure establishment time to 1.2 seconds.
Impurities in the oil circuit increase the risk of low-temperature blockage. When the gasoline gum content exceeds 30mg/100ml, the filter flow rate decreases by 70% at -10℃, and the flow rate attenuation rate reaches 0.1L per second. In 2023, the Canadian Department of Transport’s case: In the Arctic region, due to the waxing of the filter screen (0.3mm thick), the load current of the oil pump exceeded 15A (rated 10A), causing the relay to blow three times a month. Chevrolet’s technical notice states that cleaning the oil circuit every 50,000 kilometers can increase the cold start oil pressure compliance rate from 65% to 92%, and the maintenance cost is only equivalent to 20% of the total cost of replacing the Fuel Pump.
System collaborative optimization brings about breakthroughs. The Mazda SKYACTIV-X engine increases the oil pump pressure to 50MPa (20MPa in the traditional system), and in combination with piezoelectric nozzles, it achieves atomization at -30℃ for 0.5 seconds, reducing the ignition delay to 40ms. The 48V mild hybrid system of Mercedes-Benz maintains the oil pump voltage stable at 13.5V through the BSG motor, keeping the speed fluctuation rate less than ±2% and achieving a fuel supply accuracy of ±1% in extreme environments. Industry data shows that a solution integrating intelligent preheating, high-pressure injection and battery optimization can control cold start delay within one second (200% faster than the old system), saving about 1,200 yuan in rescue costs annually.