ASE L2 Domain 4: Fuel Systems Diagnosis Welcome to your ASE L2 Domain 4: Fuel Systems Diagnosis 1. ASE L2: Fuel Systems Diagnosis A diesel engine's fuel system has been contaminated with gasoline. After flushing the system and replacing the fuel, the engine runs but with reduced power and excessive smoke. What is the most likely cause? A. Clogged fuel filter. B. Damaged high-pressure pump. C. Fuel injectors sticking open. D. Aerated fuel supply. None 2. ASE L2: Fuel Systems Diagnosis During the diagnosis of a diesel engine, the technician finds metal shavings in the fuel filter. What is the MOST likely source of these shavings? A. Fuel injectors B. Fuel tank C. High-pressure fuel pump D. Fuel lines None 3. ASE L2: Fuel Systems Diagnosis A technician is diagnosing an electronically controlled diesel fuel system that has a no-start condition. The engine cranks normally. What should the technician check FIRST? A. Engine RPM sensor signal B. Glow plug system operation C. Injector pulse width D. Fuel rail pressure None 4. ASE L2: Fuel Systems Diagnosis A diesel engine with a unit injector system has a rough idle and a knock. Which of the following could be the cause? A. An injector with a delayed opening B. A worn camshaft lobe for the unit injector C. A leaking injector o-ring D. Air in the fuel system None 5. ASE L2: Fuel Systems Diagnosis A diesel engine is experiencing excessive white smoke at startup which clears after warming up. The smoke is primarily due to: A. Rich fuel mixture. B. Incomplete combustion of fuel. C. Oil entering the combustion chamber. D. Excessive EGR flow. None 6. ASE L2: Fuel Systems Diagnosis After replacing the injectors on a diesel engine, a technician notes a fluctuation in idle speed and performance. Injector adaptation has been performed. What should be checked NEXT? A. Injector electrical connections B. Fuel pressure regulator operation C. Fuel supply and return line restrictions D. Air in the fuel system None 7. ASE L2: Fuel Systems Diagnosis What could cause a diesel engine equipped with a high-pressure common rail fuel system to display a loss of power and an increased level of noise? A. A failing fuel temperature sensor B. High return flow from one or more injectors C. Restricted air filter D. Faulty turbocharger None 8. ASE L2: Fuel Systems Diagnosis During a cylinder cutout test on a diesel engine, the technician observes no change in engine running quality when one cylinder is cut out. What is the MOST likely cause? A. A faulty injector on the cylinder being cut out. B. An issue with the cylinder compression. C. A malfunction in the cylinder cutout test equipment. D. An unrelated issue with the exhaust system. None 9. ASE L2: Fuel Systems Diagnosis A diesel engine is producing excessive noise and vibration. The technician has verified that the fuel quality is good and the injectors are operating correctly. What should be checked NEXT? A. Engine mounts and brackets for integrity. B. Fuel pump timing. C. Crankshaft damper for deterioration. D. Valve clearance adjustment. None 10. ASE L2: Fuel Systems Diagnosis A technician finds that a diesel engine with common-rail injection starts hard and runs roughly when cold but improves when warm. The likely cause is: A. Weak battery or poor starter performance. B. Glow plug system faults. C. Faulty fuel pressure relief valve. D. Internal engine wear. None 1 out of 10 Time is Up! Time's up
