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Fuel system — Engineering, Mashit 30

27 questions on fuel system, from the Engineering exam of Mashit 30. Injection, injectors, fuel supply, filters and bleeding. Every question is shown with its correct answer, as in the official question pool.

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Questions on Fuel system

  1. What is characteristic of the fuel pipes from the injection pump to the injectors? They are all the same length.
  2. What is the function of the fuel injector? To spray fuel into the combustion chamber.
  3. How is the engine speed of a diesel engine changed? By controlling the governor.
  4. Which part of the fuel system determines how much fuel is injected in a diesel engine? The injection pump.
  5. What does a change in a diesel engine's power output depend on? The quantity of fuel injected.
  6. What is the function of the injection pump? To deliver fuel under pressure, correctly timed, to the injectors.
  7. What type of lift pump is commonly used in an engine's fuel system? A diaphragm pump.
  8. What is the function of the lift pump in the fuel system? To help with bleeding (priming), and to transfer fuel from the fuel tank to the injection pump.
  9. Where is the lift pump usually fitted in the fuel system? Between the tank and the fuel filter.
  10. How do you check whether fuel is reaching the injection pump? Open the air bleed screw at the pump outlet.
  11. What can the sediment in the fuel system consist of? Solid particles.
  12. What is the function of the injector in a diesel engine? To break the fuel up into a fine spray and spray it into the combustion chamber.
  13. What is the function of the governor in a diesel engine? To keep the engine running at the desired, steady speed.
  14. What is the main purpose of the fuel system in a diesel engine? To spray fuel into the combustion chamber with precise timing and in a precise quantity.
  15. When is the risk of an explosion in the fuel tank greater? When the tank is almost empty.
  16. What sediment is usually found in the fuel tank of a diesel engine? Bacteria and fungi that have grown in the fuel tank.
  17. What is generally true of the pipes that carry fuel from the injection pump to the injectors? They are usually all the same length and withstand high pressure.
  18. What is the purpose of the vent pipe fitted to the fuel tank? To let the tank breathe and keep the pressure in the tank equal to atmospheric pressure.
  19. If a diaphragm-type lift pump is not pumping, what could be the cause? All of the above.
  20. What does the stop handle control? The governor.
  21. What does the throttle lever control? Answers a and c are correct.
  22. What is the function of the injection pump? To deliver fuel to the injectors at high pressure, in varying quantities and with precise timing.
  23. What is the most common fault in diesel engines? Air getting into the fuel system.
  24. What is the purpose of the vent (breather) fitted to the fuel tank? To let the tank "breathe", balancing it with air, when refuelling or when fuel is drawn off.
  25. What should you do after finding air in the fuel system? Bleed the air out of the fuel system.
  26. What is the function of the governor in a diesel engine? It keeps the desired engine speed (rpm) by acting on the injection pump.
  27. What is needed to "prime" (bleed the air from) the injector pipes? Turn the engine over continuously (the crankshaft) and slacken the pipe unions at the injectors.

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