In case of all gasoline vehicles such as the passenger vehicle, heavy duty truck and light duty truck etc., a fuel pump is located inside the fuel tank and transfers the fuel to an engine for stable driving, however, engine stall can be occurred by low pressure fuel pump. The boiling temperature of gasoline fuel is very low, the initial boiling point is around 40°C so fuel can boil easily while driving and end boiling point is around 190°C. It boils sequentially depending on the temperature. It becomes the criteria to determine the amount of vapor released inside the fuel tank at high temperature. The main cause of engine stall at high temperature is rapid fuel boiling by increasing fuel temperature. This causes a lot of vapor. Such vapor flows into the fuel pump which leading to decrease the pump load and the current consumption of the fuel pump continuously. This ultimately results in engine stall. The influence on Reid Vapor Pressure(RVP) was also investigated, but it does not seem to have a significant effect on engine stall. Since vapor pressure is involved in the amount of evaporation, it is judged that it does not absolutely affect the amount of vapor generated at high temperatures. The effect on fuel tank inner pressure was also evaluated. When the internal tank pressure abruptly decreases during driving, the boiling amount of the fuel suddenly increases, which leads to create a lot of vapor in the fuel, resulting in engine stall. In this study, the effect of the boiling point, vapor pressure, weathering of fuel on engine stall was also researched. This paper is the result of finding the root-cause of engine stall at hot ambient from a perspective low pressure fuel pump.