Accidental fueling is a common problem these days. With three types of fueling options available on a pumping station, a person can accidentally stand in the incorrect lane. But the problem arises when people face the consequences of this problem. The engine of the car is designed to run on a specific fuel type which corresponds to the weight of the fuel. The method of ignition of diesel and petrol are different in the automobiles, additionally, the types of engines for these fuels are also different.
The diesel engine is also known as a compression engine and uses and internal combustion to ignite. It means that the fuel that has been injected into the combustion chamber is compressed at high pressure to gain high temperature which ignites the diesel fuel. This contrasts with petrol engine which uses spark to ignite the petrol. The difference in ignition styles is because diesel is a heavy fuel; it contains many hydrocarbons which make it quite difficult to ignite by a small spark.
On the other hand, petrol is a very light liquid and due to its low number of hydrocarbons requires a very small spark to ignite. The combustion mechanism of the diesel engine involves allowing the air into the combustion cylinder and the piston compresses it up to 14-25 times of its original volume, resulting in an increased temperature of about 500°C. Once the required compression is achieved, a mist of fuel is sprayed over the air by an electronic fuel injection system which is akin to an aerosol can. The air is so hot that the fuel instantly ignites without the need of a spark plug.
Firstly, it is almost impossible to fill a petrol car with diesel, because, the nozzle of the diesel pipe is bigger than the filler neck on the petrol cars. A plate is present under the neck to prevent any intrusion but the small petrol nozzle, which was designed to prevent this problem in the first place. Even if you accidentally somehow inject diesel in a petrol car you will not be able to start it.
The reason is explained above that the injectors will inject diesel into the combustion chamber but the spark plug will not be able to ignite it because of the high viscosity and ignition point of the diesel. Even if it will start, it will cause large plumes of gray smoke due to incomplete combustion and will lead to overheating of the engine and will cause the spark plugs and the fuel system to clog.
The classic signs of diesel of accidental injection of diesel in a petrol car are the misfiring of the engine, the engine might not tart at all, the engine gets cut out and smoky exhaust when driving. You need to go to a mechanic immediately if you see these signs. He will drain out the entire fuel chamber; clean the spark plugs and combustion chamber. Cleaning of the spark plugs is a must because the main obstruction is present there. After cleaning you will see smoke which will be due to residual diesel cleaning up and then your car will run like before.