Why is clean fuel essential for metering accuracy?

• A. Clean fuel reduces fuel economy
• B. Contaminants can clog jets, nozzles, seals, and sensors, altering flow and AFR
• C. Contaminants improve lubricity
• D. Clean fuel decreases octane

Answer: (B)

Clean fuel is essential for metering accuracy because the fuel metering system relies on delivering a precise amount of fuel through very small passages. Contaminants such as particulates, varnish, or moisture can clog jets, nozzles, seals, and even sensors, changing the actual flow from what the control system intends. That disruption shifts the fuel-air ratio away from the commanded value, causing lean or rich conditions, unstable idle, misfires, or degraded performance. Debris and deposits can also affect injector spray patterns and pressure regulation, making metering even less predictable over time. The other ideas don’t fit because contaminants don’t improve lubricity, and octane isn’t reduced by cleanliness; nor does clean fuel inherently improve or reduce fuel economy in a way that would offset the need for accurate metering.