Which action in high-pressure fuel lines can alter the timing of fuel delivery?

• A. Increasing line length
• B. Increasing line diameter
• C. Bending the line
• D. Replacing with heavier metal

Answer: (C)

In high-pressure fuel lines, the exact moment the injector opens depends on how quickly the pressure pulse from the pump reaches the injector. Bending the line changes its path and stiffness, which can alter how the pressure wave propagates, including any slight reflections or damping along the route. These changes can shift the time it takes for the fuel to reach the injector at the required pressure, effectively altering delivery timing. Other actions—like simply making the line longer, using a larger diameter, or a heavier metal—affect flow characteristics or line volume more than the pressure-wave timing, so they don’t influence the precise moment of injection in the same direct way.