If you're low on gas, can you actually run on fumes?
The short answer is no. For the long answer, AF turns to Gary Pollak at the Society of Automotive Engineers: "The way the internal combustion engine is designed, there's a small combustion chamber above the piston" where the fuel and air mix. "The fuel is injected into that chamber via a pump, and that pump pumps liquid. Once that fuel flow stops — as soon as there's no more liquid in that line — there's not enough fuel in the air to support the combustion and the combustion stops. So there really is no such thing as running on fumes."
Ray Rust, mechanical-engineering academic lab coordinator at Kettering University in Flint, Michigan, notes that "every time you fill it, gunk gets into the gas tank and settles into the lowest point [and] winds up around the fuel pickup nozzle if that's the only fuel left in the tank. So if you keep running your tank low, you're more likely to suck up small particles and clog up your fuel filter. Also, the lower the tank [level] is, the more work that pump has to do."
Rust's advice? Keep your tank at least half full. And don't get hit by that second punch.
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