ASE4 Fuel, Air Induction, and Exhaust Systems

Question 1

A fuel pressure test shows correct pressure at idle but drops significantly under full throttle acceleration. This indicates:

Accepted Answer

A restricted fuel filter or weak fuel pump

Answer

A leaking fuel pressure regulator

Answer

A faulty MAP sensor

Answer

Stuck-open fuel injectors

Question 2

A technician performs a fuel injector balance test. One injector causes a smaller pressure drop than the others. This means that injector is:

Accepted Answer

Flowing too little fuel (clogged or weak)

Answer

Flowing too much fuel (stuck open)

Answer

Working normally

Answer

Leaking when the engine is off

Question 3

A vacuum-controlled fuel pressure regulator is removed and inspected. Fuel is found in the vacuum port. This indicates:

Accepted Answer

The regulator diaphragm has failed, allowing fuel into the vacuum system

Answer

The regulator is operating normally under boost

Answer

The fuel pressure is too high

Answer

The intake manifold has a vacuum leak

Question 4

An engine equipped with port fuel injection has a rough idle that improves when the air filter is removed. This MOST likely indicates:

Accepted Answer

A severely restricted air filter causing a lean condition

Answer

A rich air/fuel mixture

Answer

A faulty MAF sensor

Answer

A vacuum leak past the throttle plate

Question 5

What is the purpose of the exhaust back-pressure test?

Accepted Answer

To detect a restricted catalytic converter or exhaust system

Answer

To measure combustion efficiency

Answer

To test oxygen sensor response time

Answer

To measure EGR valve flow

Question 6

A technician finds fuel pressure holds for 30 seconds after the engine is shut off but then bleeds down slowly over several minutes. This MOST likely indicates:

Accepted Answer

A leaking fuel injector

Answer

A faulty check valve in the fuel pump

Answer

Normal pressure bleed-down for a returnless system

Answer

A failing fuel pressure regulator