HD3 Gasoline Systems

An average mixtures of air to gasoline for a moderate cruising speed is approximately:

8:1

10:1

15:1

25:1

Correct! Wrong!

The amount of pressure the fuel pump exerts on the fuel line to the carburetor depends on the strength of the:

diaphragm spring

length of rocker arm

pull rod movement

number of strokes/min

Correct! Wrong!

The advantage of an electric fuel pump over a manual fuel pump is that the electric fuel pump can:

be mounted in a location to push the fuel rather than suck it

fill the carburetor bowl without having to crank the engine

may be mounted away from the heat of the engine

all of the above

Correct! Wrong!

The advice that controls fuel entry into a carburetor by adjusting a needle position relative to its seat in a fuel bowl is known as a(n):

metering rod

float

air bleed

main discharge tube

Correct! Wrong!

The main discharge tube, which runs from the _________________ through the metering jets, to the air intake above the venturi.

fuel pump

intake manifold

float bowl

air horn

Correct! Wrong!

The carburetor''s low speed circuit functions when the vehicle is at low speed and:

partial throttle

full throttle

no throttle

all of the above

Correct! Wrong!

The main jets and metering rods controls the amount of fuel that is metered into the _______________ in the air horn and carburetor''s venturi

float bowl

charcoal canister

accelerator pump

discharge tube

Correct! Wrong!

The item used to create a vacuum at the venturi strong enough to draw a substantial amount of fuel from the main discharge nozzle when cranking, is known as a (n):

choke valve

throttle valve

balance tube

all of the above

Correct! Wrong!

The item used to prevent a "flat spot" or "hesitation" and inject more fuel when the throttle is snapped to the full open position is known as a (n):

booster venturi

metering rod

power valve

accelerator pump

Correct! Wrong!

There are three types of vacuum created by an engine, one in the intake manifold below the throttle plates and another in the carburetor''s venturi and the ported vacuum.

true

false

Correct! Wrong!

A loose carburetor mounting to the intake manifold may cause:

the engine to run with a lean mixture

poor idling

hesitation

all of the above

Correct! Wrong!

How many "circuits" are there in most automotive carburetors?

three

five

seven

nine

Correct! Wrong!

On sequential gasoline multiport fuel injection systems, the fuel injectors inject fuel:

in the engine firing order

twice per cylinder

in random pulses

above the throttle plates

Correct! Wrong!

A mass airflow sensor (MAF) may use a __________________ to determine air flow.

hot wire

frequency

potentiometer

all of the above

Correct! Wrong!

The primary function of the throttle air bypass valve is to control ___________________.

manifold pressure

throttle plate position

fuel pressure

idle speed

Correct! Wrong!

When does the idle air control valve (IAC) control airflow?

warm idle

cruise

cold idle

both A and C

Correct! Wrong!

The primary function of the inertia switch is to control power to the _________________ in the event of an accident.

fuel pump

engine

ECM

ignition

Correct! Wrong!

Engine coolant and charge air temperature sensors are both _______________type sensors.

thermistor

switch

potentiometer

actuator

Correct! Wrong!

Throttle position (TPS) provide a (an) ________________ voltage signal:

analog

digital

temperature

barometric

Correct! Wrong!

NOx emissions may be reduced by:

retarding ignition timing

lower compression ratios

user of EGR valves

all of the above

Correct! Wrong!

O2 sensors can be contaminated by:

leaded fuel

oil

carbon

all of the above

Correct! Wrong!

Fuel quantity is controlled by the PCM by signalling injector ______________.

pulse width

duty cycle

metering valve

stepper motor

Correct! Wrong!

Technician A says that a Mass Airflow Sensor may use a hot wire or heated film. Technician B says that a Mass Airflow Sensor may use a potentiometer.

Technician A

Technician B

Both A and B

Neither A nor B

Correct! Wrong!

Throttle body fuel injection uses one injector for each cylinder in the engine.

true

false

Correct! Wrong!

All multiport fuel injection uses one injector for each cylinder in the engine.

true

false

Correct! Wrong!

Technician A says that fuel regulators are always on the upstream (inlet) side of the injector. Technician B says that the fuel pressure regulator outlet is incorporated into the fuel lines returning to the tank.

Technician A

Technician B

Both A and B

Neither A nor B

Correct! Wrong!

Technician A says that when the vehicle is not running there is no fuel pressure at the injectors. Technician B says that if the system is working properly, there should be residual pressure but it will be different on throttle body and multiport systems.

Technician A

Technician B

Both A and B

Neither A nor B

Correct! Wrong!

To prevent a build up of excess pressure in the fuel tank, older style filter caps may have:

an open vent

a relief valve

a hinge

a special restrictor

Correct! Wrong!

To help prevent the formation of vapor in the fuel line, some filters and/or fuel pumps will have:

a relief valve

a spring

a high micron paper element

a return line

Correct! Wrong!

Generally, with a mechanical fuel pump, motion is provided to the diaphragm by:

a crankshaft

a special pulley

a camshaft

an electric motor

Correct! Wrong!

All fuel lines in the vehicle that are attached to the frame or engine are made of specialized composite materials or:

copper

aluminum

steel

rubber

Correct! Wrong!

In a carburetor, when air flows through and leaves the venturi, the velocity will tend to:

decrease in pressure

Correct! Wrong!

The ability of a fuel to evaporate is called:

atomization

cetane rating

volatility

octane rating

Correct! Wrong!

The complete combustion of the precisely controlled fuel and air mixture in the engine cylinders is called stoichiometric ratio:

true

false

Correct! Wrong!

During heavy load operation the engine will require:

leaner mixtures

less fuel

more fuel

higher speeds

Correct! Wrong!

In a carburetor, the system or circuit that provides fuel during normal engine cruise operation is the:

accelerator pump

power enrichment circuit

choke circuit

main metering circuit

Correct! Wrong!

The amount of fuel that the main metering system can supply depends on:

the size of the venturi

the size of the jets

the size of the float bowl

the size of the booster venturi

Correct! Wrong!

Before beginning any service on the fuel system you should:

drain the fuel tanks.

review the manufacturer's requirements.

make sure all the shop doors are open.

turn off all electrical devices.

Correct! Wrong!

Exhaust gas analyzers are designed to read emissions from the vehicle after combustion has occurred.

true

false

Correct! Wrong!

The two most important tests performed on a mechanical fuel pump are:

vacuum and draw

speed and volume

pressure and volume

pressure and vacuum

Correct! Wrong!

For safety reasons, before removing any fuel system components you should:

remove the ignition key

remove all fuel lines

disconnect the ignition wiring

remove the battery ground terminal

Correct! Wrong!

When diagnosing a poor operation complaint, and before opening any fuel system for repair, you should always check to make sure that there are not other basic problems with the vehicle''s primary and secondary electrical systems.

true

false

Correct! Wrong!

Fuel delivery to the cylinders within a modern computerized fuel system is achieved by using:

a carburetor

solenoid venturi feedbacks

variable venturi feedbacks

EGR valve modifiers

Correct! Wrong!

One factor that allows accurate vehicle operation, is that the computer is constantly changing the ignition timing and fuel delivery to account for changes in vehicle operation.

true

false

Correct! Wrong!

The sensor that indicates changes due to temperature is the:

signal generator

potentiometer

thermistor

switch

Correct! Wrong!

A throttle position sensor is an example of a:

potentiometer

thermistor

switch

hot-wire

Correct! Wrong!

The oxygen sensor monitors:

only the exhaust air/fuel ratio

exhaust air/fuel ratio and spark timing

spark timing only

all of the engine operation

Correct! Wrong!

Before disconnecting the battery on a computer controlled vehicle, you should:

scan and retrieve any trouble codes

take the vehicle for a thorough test drive

reset the clock

check all the computer connections

Correct! Wrong!

You can check the operation of each fuel injector solenoid by:

removing one spark plug wire at a time

disconnecting the fuel pump fuse

installing a special calibration unit in the computer

listening to each one with a stethoscope

Correct! Wrong!

Throttle body injection units are sealed for life and never need service.

true

false

Correct! Wrong!

An average mixtures of air to gasoline for a moderate cruising speed is approximately:

The amount of pressure the fuel pump exerts on the fuel line to the carburetor depends on the strength of the:

The advantage of an electric fuel pump over a manual fuel pump is that the electric fuel pump can:

The advice that controls fuel entry into a carburetor by adjusting a needle position relative to its seat in a fuel bowl is known as a(n):

The main discharge tube, which runs from the _________________ through the metering jets, to the air intake above the venturi.

The carburetor''s low speed circuit functions when the vehicle is at low speed and:

The main jets and metering rods controls the amount of fuel that is metered into the _______________ in the air horn and carburetor''s venturi

The item used to create a vacuum at the venturi strong enough to draw a substantial amount of fuel from the main discharge nozzle when cranking, is known as a (n):

The item used to prevent a "flat spot" or "hesitation" and inject more fuel when the throttle is snapped to the full open position is known as a (n):

There are three types of vacuum created by an engine, one in the intake manifold below the throttle plates and another in the carburetor''s venturi and the ported vacuum.

A loose carburetor mounting to the intake manifold may cause:

How many "circuits" are there in most automotive carburetors?

On sequential gasoline multiport fuel injection systems, the fuel injectors inject fuel:

A mass airflow sensor (MAF) may use a __________________ to determine air flow.

The primary function of the throttle air bypass valve is to control ___________________.

When does the idle air control valve (IAC) control airflow?

The primary function of the inertia switch is to control power to the _________________ in the event of an accident.

Engine coolant and charge air temperature sensors are both _______________type sensors.

Throttle position (TPS) provide a (an) ________________ voltage signal:

NOx emissions may be reduced by:

O2 sensors can be contaminated by:

Fuel quantity is controlled by the PCM by signalling injector ______________.

Technician A says that a Mass Airflow Sensor may use a hot wire or heated film. Technician B says that a Mass Airflow Sensor may use a potentiometer.

Throttle body fuel injection uses one injector for each cylinder in the engine.

All multiport fuel injection uses one injector for each cylinder in the engine.

Technician A says that fuel regulators are always on the upstream (inlet) side of the injector. Technician B says that the fuel pressure regulator outlet is incorporated into the fuel lines returning to the tank.

Technician A says that when the vehicle is not running there is no fuel pressure at the injectors. Technician B says that if the system is working properly, there should be residual pressure but it will be different on throttle body and multiport systems.

To prevent a build up of excess pressure in the fuel tank, older style filter caps may have:

To help prevent the formation of vapor in the fuel line, some filters and/or fuel pumps will have:

Generally, with a mechanical fuel pump, motion is provided to the diaphragm by:

All fuel lines in the vehicle that are attached to the frame or engine are made of specialized composite materials or:

In a carburetor, when air flows through and leaves the venturi, the velocity will tend to:

The ability of a fuel to evaporate is called:

The complete combustion of the precisely controlled fuel and air mixture in the engine cylinders is called stoichiometric ratio:

During heavy load operation the engine will require:

In a carburetor, the system or circuit that provides fuel during normal engine cruise operation is the:

The amount of fuel that the main metering system can supply depends on:

Before beginning any service on the fuel system you should:

Exhaust gas analyzers are designed to read emissions from the vehicle after combustion has occurred.

The two most important tests performed on a mechanical fuel pump are:

For safety reasons, before removing any fuel system components you should:

When diagnosing a poor operation complaint, and before opening any fuel system for repair, you should always check to make sure that there are not other basic problems with the vehicle''s primary and secondary electrical systems.

Fuel delivery to the cylinders within a modern computerized fuel system is achieved by using:

One factor that allows accurate vehicle operation, is that the computer is constantly changing the ignition timing and fuel delivery to account for changes in vehicle operation.

The sensor that indicates changes due to temperature is the:

A throttle position sensor is an example of a:

The oxygen sensor monitors:

Before disconnecting the battery on a computer controlled vehicle, you should:

You can check the operation of each fuel injector solenoid by:

Throttle body injection units are sealed for life and never need service.

Success!

Heavy-Duty Mechanic - Trucks & Equipment