What is a common cause of air in the fuel lines in a gasoline engine?

What is a common cause of air in the fuel lines in a gasoline engine?

• A. Leaking fuel injector
• B. Low fuel pressure
• C. Running out of fuel
• D. Cracked fuel line

Answer: (C)

Air in the fuel line happens most often when there isn’t enough liquid fuel to fill the line, such as when you run the tank dry. When the tank is empty, the fuel pump starts pulling air along with whatever tiny amount of fuel remains, creating air pockets and bubbles in the line. Those bubbles disrupt a steady flow of fuel to the injectors, causing hard starting, misfires, rough running, or stalling as the engine tries to run on air instead of fuel. Leaking fuel injectors would show fuel leaks rather than a supply of air, so they don’t typically cause air to be drawn into the line. Low fuel pressure can cause the engine to run poorly, but it doesn’t inherently introduce air into the line. A cracked fuel line can leak fuel, and while it’s a serious fault, it’s not the common cause of air in the line in normal operation; the line usually fills with air primarily when the tank is empty.

Air in the fuel line happens most often when there isn’t enough liquid fuel to fill the line, such as when you run the tank dry. When the tank is empty, the fuel pump starts pulling air along with whatever tiny amount of fuel remains, creating air pockets and bubbles in the line. Those bubbles disrupt a steady flow of fuel to the injectors, causing hard starting, misfires, rough running, or stalling as the engine tries to run on air instead of fuel.

Leaking fuel injectors would show fuel leaks rather than a supply of air, so they don’t typically cause air to be drawn into the line. Low fuel pressure can cause the engine to run poorly, but it doesn’t inherently introduce air into the line. A cracked fuel line can leak fuel, and while it’s a serious fault, it’s not the common cause of air in the line in normal operation; the line usually fills with air primarily when the tank is empty.