Step 3 » GENERAL learning environment Category B (B, B1)

For answer  A 

The lack of fuel causes intermittent engine operation until it stops completely, but it does not lead to the emission of excessive smoke.

For answer  B 

The fuel tank cap must be properly closed to prevent impurities or other liquids from entering the tank, but this aspect is not related to the occurrence of excessive smoke.

For answer  C 

The injection system of a Diesel engine is a high‑precision system consisting of the injection pump, high‑pressure pipes and injectors. The pump sends the diesel fuel with high pressure to the injectors, in the firing order, and regulates the fuel flow depending on the operating regime. The high‑pressure pipes transport the diesel fuel to the injectors, which dose it and finely spray it into the combustion chamber.

A malfunction of the injection system can lead to an excessive amount of diesel fuel in the cylinders, affecting the combustion process and generating excessive black smoke. Thus, excessive smoke emission in a Diesel engine is usually caused by a malfunction of the injection system.

The correct answer is: C

Recommendations:

Mechanics course (knowledge of the main elements) --> Mechanics course