A: General Engine Diagnosis; Tasks 1-9 Questions And Answers

1. While discurssing a basic diagnostic procedure, Technician A says that the most complicated
diagnostic tests should be performed first. Technician B says that the customer complaint must be
identified. Who is correct?
A. A only - B. B only - C. Both - D. Neither - ANS-✔✔B - The easiest, quickest test should be performed
first. The customer complaint must be identified during a basic diagnostic procedure.
2. A throttle body injected engine has a no-start complaint, and no fuel is discharged from the injectors
when the engine is cranking. Technician A says to check the voltage supply to the fuel pump. Technician
B says to check the fuel filter for a partial restriction. Who is correct?
A. A only - B. B only - C. Both - D. Neither - ANS-✔✔A - Technician B is incorrect because with a partially
restricted fuel filter, some fuel is still discharged from the injectors. Technician A is correct because if
there is no voltage supplied to the fuel pump, the fuel pressure is zero, and no fuel is discharged from
the injectors.
3. A cooling system is pressurized with a pressure tester to locate a coolant leak. After 15 minutes, the
tester gauge has dropped from 15 psi to 5 psi, and there are no visible signs of coolant leaks in the
engine compartment. Technician A says that the engine may have a leaking head fasket. Technician B
says that the heater core may be leaking. Who is correct?
A. A only - B. B only - C. Both - D. Neither - ANS-✔✔C - Technicians A & B because neither a leaking
head fasket nor heater core will cause leaks in the engine compartment, but they will reduce the test
pressure.
4. A heavy thumping noise occurs with the engine idling, but the oil pressure is normal. This noise may
be caused by:
A. worn pistons and cylinders - B. loose flywheel bolts
C. Worn main bearings - D. loose camshaft bearings - ANS-✔✔B - Worn pistons and cylinders would
cause a rapping noise while accelerating, and worn main bearings would cause a thumping noise when
the engine is started. Therefore, A and C are incorrect. Loose camshaft bearings usually do not cause a
noise unless severely worn, so D is incorrect. Loose flywheel bolts may cause a thumping noise at idle.