Which engines must be shut off before fueling?

• A. Non-diesel internal combustion engines
• B. Diesel engines
• C. All engines
• D. Electric engines

Answer: (A)

Fueling safety hinges on removing sources of ignition from the fueling area. Gasoline-powered engines use spark-ignition and typically have hot surfaces and electrical components that can spark. When fuel vapors are present, those sparks can ignite them, so shutting off these engines eliminates the main ignition source right at the fueling point. Diesel engines don’t rely on a spark for combustion, and diesel fuel has a higher flash point, making ignition from a nearby engine less likely. Electric engines don’t involve combustion or ignition sources in the same way, so they don’t introduce the same risk during fueling. So the rule is to shut off the non-diesel internal combustion engines before fueling.