Oilers/Plant Tenders (HHC) Civil Service Practice Exam

In the fuel system for a 4-stroke cycle diesel engine, where does the oil flow sequentially from the fuel tank?

1. Injection pump, filters, injection valve

2. Transfer pump, filters, injection pump, injection valve, pre-combustion chamber

3. Filters, transfer pump, pre-combustion chamber

4. Injection valve, tank, filters

The correct answer is: Transfer pump, filters, injection pump, injection valve, pre-combustion chamber

The correct sequence of oil flow in the fuel system of a 4-stroke cycle diesel engine is from the fuel tank through a transfer pump, followed by filters, then to the injection pump, and subsequently to the injection valve, before entering the pre-combustion chamber. Beginning with the fuel tank, the transfer pump's role is crucial as it moves fuel from the tank to the next stage of the system. After this initial movement, the fuel passes through filters that remove any impurities and contaminants, ensuring that the fuel delivered to the engine components is clean. This is particularly important in maintaining the efficiency and longevity of the engine. The clean fuel is then directed towards the injection pump, which pressurizes it, allowing it to flow at the correct rate and pressure to meet the engine's needs. The next step involves the fuel being fed to the injection valve, which controls the timing and quantity of fuel injected into the pre-combustion chamber. This sequencing is vital for the proper functioning of the engine's combustion process. This flow sequence highlights the importance of each component in ensuring that the fuel delivered to the engine is both sufficient in quantity and quality, facilitating efficient operation and reducing the risk of damage or inefficiency.