What is the temperature threshold at which fuel systems are designed to avoid vapor lock?

Fuel systems are engineered with safety margins to prevent vapor lock, which occurs when fuel vaporizes in the fuel lines or mechanical components, leading to a loss of engine power. The correct temperature threshold for avoiding vapor lock is established based on the physical properties of fuel and its behavior at various temperatures.

When temperatures surpass 110 degrees Fahrenheit, the risk of vapor lock significantly increases because the volatility of the fuel rises with temperature. At this threshold, fuel can more readily vaporize, especially in low-pressure areas of the fuel system, which can lead to operational issues such as hard starting, engine stalling, or reduced power output. Therefore, fuel system designs typically incorporate features and materials that ensure adequate function and vapor resistance at temperatures below this threshold, effectively mitigating the risk of vapor lock during operation.

Considering the other choices, temperatures below 32 degrees Fahrenheit and below 50 degrees Fahrenheit may lead to other concerns, such as fuel gelling, especially in certain diesel fuels, but they are not directly tied to vapor lock. Similarly, while temperatures above 80 degrees Fahrenheit also increase the risk of vapor lock, they do not provide the comprehensive safety margin that is present at the established threshold of 110 degrees Fahrenheit, thus leading to its selection as the most