310T Engine and Fuel Systems 3

Question 1

A diesel engine exhibits excessive white smoke at startup that clears after warm-up. What is the most likely cause?

Accepted Answer

Incomplete fuel combustion due to cold engine

Answer

Worn piston rings

Answer

Low compression in one cylinder

Answer

Stuck open injector

Question 2

On a common rail diesel fuel system, what component maintains system pressure between injection events?

Accepted Answer

High-pressure accumulator rail

Answer

Fuel lift pump

Answer

Fuel pressure regulator valve

Answer

Injection control pressure sensor

Question 3

Which condition would cause a diesel engine to run rough and produce black smoke under load?

Accepted Answer

Restricted fuel filter

Answer

Air in the fuel system

Answer

Clogged EGR valve

Answer

Leaking fuel injector return line

Question 4

When performing a diesel engine compression test, a reading of 380 psi on one cylinder versus 480 psi on all others indicates:

Accepted Answer

Worn or damaged rings or valves in that cylinder

Answer

Normal variation within specification

Answer

Incorrect test procedure

Answer

Faulty compression gauge

Question 5

A technician notices the crankcase pressure is excessive and oil is pushed out through seals. What test should be performed first?

Accepted Answer

Cylinder leakdown test

Answer

Fuel pressure test

Answer

Coolant pressure test

Answer

Turbocharger boost pressure test

Question 6

What is the purpose of the fuel return line on a diesel injection system?

Accepted Answer

To return excess fuel and cool the injectors back to the tank

Answer

To supply additional fuel during high load

Answer

To recirculate fuel through the water separator

Answer

To bypass the fuel filter under high demand

Question 7

A truck's engine idles smoothly but stumbles when throttle is applied quickly. On a diesel, this most likely indicates:

Accepted Answer

Turbocharger lag or restricted intake

Answer

Faulty throttle position sensor

Answer

Worn camshaft lobes

Answer

Low engine oil pressure