How a trip back into the car can spark a fire
The risky action is getting back into the vehicle while fuel is flowing, then stepping out and reaching for the pump nozzle. Sliding across a car seat and standing up can build static electricity on a person, especially in dry conditions. If that charge jumps from a hand to the nozzle or the vehicle’s metal near the filler opening, the tiny spark can ignite gasoline vapor.
Why the flame can appear suddenly
Gasoline gives off vapor that can mix with air around the open filler neck. A spark needs very little energy to ignite that mixture. The result may be a brief flash fire around the nozzle and fuel opening—not necessarily an explosion of the whole tank. The danger is that a startled person may drop the nozzle or spill fuel, giving the fire more to catch.
Stay outside while fueling
The simplest precaution is not to re-enter the car until fueling is finished. If you do get back in, touch a metal part of the vehicle away from the filler opening before handling the nozzle again; that can let built-up charge discharge before it reaches the vapor. A routine pause in the middle of fueling can turn a harmless static snap into a fire hazard.
