ASE Light Vehicle Diesel Engines 2

Question 1

In a common rail diesel injection system, what component is primarily responsible for generating the extremely high fuel pressure?

Accepted Answer

High-pressure fuel pump

Answer

Lift pump

Answer

Injector solenoid

Answer

Fuel rail sensor

Question 2

A diesel engine has hard starting when cold but runs fine once warm. Which system should you inspect first?

Accepted Answer

Glow plug system

Answer

EGR valve

Answer

Turbocharger wastegate

Answer

Fuel return line

Question 3

What is the purpose of the diesel particulate filter (DPF) regeneration process?

Accepted Answer

Burn off accumulated soot

Answer

Cool the exhaust gas

Answer

Increase fuel rail pressure

Answer

Recharge the glow plugs

Question 4

Excessive black smoke from a diesel under load most commonly indicates which condition?

Accepted Answer

Incomplete combustion from too much fuel or too little air

Answer

Coolant entering the cylinders

Answer

Worn glow plugs

Answer

Low battery voltage

Question 5

Which sensor signals the PCM about the position and speed of the crankshaft for diesel injection timing?

Accepted Answer

Crankshaft position sensor

Answer

MAP sensor

Answer

Coolant temperature sensor

Answer

Oxygen sensor

Question 6

What does a glow plug 'wait-to-start' lamp indicate to the driver?

Accepted Answer

Glow plugs are still preheating the cylinders

Answer

The DPF is regenerating

Answer

Oil pressure is low

Answer

The turbo is spooling

Question 7

Why is using clean, properly filtered fuel especially critical in modern high-pressure common rail diesels?

Accepted Answer

Tight injector tolerances are easily damaged by contaminants

Answer

Fuel additives are illegal

Answer

The lift pump cannot move dirty fuel

Answer

Glow plugs require ultra-clean fuel