Once went on a trip with my uncle. He was drinking a can of beer while driving us around. Pulled up to a pump and gets out and starts pumping gas. After a minute I realize he never turned off the truck. Apparently left it running every time.
You can do that with modern cars, the risk is essentially zero. It’s more dangerous to not ensure you’re statically discharged / not get in and out of the car
But you really shouldn’t, as the evaporative emissions system isn’t designed for that.
Modern vehicles use a charcoal canister open to atmosphere to absorb gasoline vapors as they exit the tank when the car is off. They do this through a purge valve that opens only when the engine is off. When the engine is running, the purge valve closes and a second valve opens sucking gasoline vapors into the intake manifold vacuum, where they can be easily burned by the engine.
By refuelling with the engine on this purge valve is closed and you risk ejecting a stream of extra gasoline into the engine (depending on the quality of the evap system and whether it can detect tank pressure changes to open the purge valve). Have had this happen on older cars where the engine wouldn’t run after refuelling because the manifold valve wouldn’t close and it just filled the intake with liquid gas, flooding out the engine.
Once went on a trip with my uncle. He was drinking a can of beer while driving us around. Pulled up to a pump and gets out and starts pumping gas. After a minute I realize he never turned off the truck. Apparently left it running every time.
You can do that with modern cars, the risk is essentially zero. It’s more dangerous to not ensure you’re statically discharged / not get in and out of the car
But you really shouldn’t, as the evaporative emissions system isn’t designed for that.
Modern vehicles use a charcoal canister open to atmosphere to absorb gasoline vapors as they exit the tank when the car is off. They do this through a purge valve that opens only when the engine is off. When the engine is running, the purge valve closes and a second valve opens sucking gasoline vapors into the intake manifold vacuum, where they can be easily burned by the engine.
By refuelling with the engine on this purge valve is closed and you risk ejecting a stream of extra gasoline into the engine (depending on the quality of the evap system and whether it can detect tank pressure changes to open the purge valve). Have had this happen on older cars where the engine wouldn’t run after refuelling because the manifold valve wouldn’t close and it just filled the intake with liquid gas, flooding out the engine.
I don’t think my dad has ever turned off his car at the pump