Without human intervention - the engine loses either the fuel supply or ignition failure and the engine stops.
With human intervention the clutch is released too fast or with not enough fuel supplied and the engine loses enough rpm that it cannot continue to run and stops.
Stall = User error.
There is a difference between a car stalling and a car cutting out as it has a fault.
Only two things - electrical or gas.
The electrical system can fail - the coil can stop producing enough spark or something mechanical breaks in the ignition system. But mostly it just means no spark to the fuel.
And then the fuel can run out or be blocked up in the fuel line somehow.
Because something interrupts fuel, air, spark, or the engine is worn out and the compression is too low, or many other malfunctions I could name.
In simple terms!
