I have a diesel engine running. And I switched the diesel fuel to gasoline fuel. It does not ignite at all. Why ?
Diesel and petrol/gasoline are totally different fuels, and work in different ways.
Diesel engines are known as 'compression ignition' - Diesel fuel is heavy and has low volatility (meaning that it doesn't burn well), and in a Diesel engine is it injected into a cylinder full of compressed air at a high pressure and temperature, which causes the fuel to ignite.
In a petrol engine on the other hand, the fuel is much thinner, lighter and more volatile, and is ignited by means of a spark - these engines run at much lower pressure.
The two are not compatible, and neither fuel will work in an engine designed for the other.
Diesel is compression ignition and the gasoline engine is spark ignition..
So you need to provide a spark to ignite the gasoline.
However, in some situations you can get run away of diesel engines where uncontrolled fuel or oil is causing the engine to continue running - these can actually over- rev and fail.