How much water would it take to stall a car?

Answer 1

Water is heavier than gasoline and the pick up tube is located at the lowest point in the fuel tank so, to stall a car and cause it not to restart, I would guess several ounces would be enough once the water has been pumped up to the engine.

Answer2:It really depends on where the water is. Water outside the car won't stall it until it reaches the air inlet. At that point, a single drop touching an airflow metering sensor can be enough. Absent an airflow metering sensor, it would take a lot of water to block an air filter.

Inside an engine's combustion chamber, it can take only teaspoons to stop the engine turning or cause the engine to physically break.

In a fuel line, sufficient water to be insoluble (typically about 2%) or so will do the trick, alcohol fuels excluded. Some alcohol fueled vehicles can tolerate (but not happily) more than 15% water in the fuel.