HD Gasoline Systems

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

8:1

10:1

15:1

25:1

Correct! Wrong!

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

strength of the diaphragm or plunger spring.

length of rocker arm.

lift of the camshaft eccentric.

number of strokes per minute.

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 device 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 runs from the through the metering jets, to the air intake above the carburetor 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 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 know 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 vacuums created by an engine and carburetor: 1. in the intake manifold below the throttle plates, and 2. in the carburetor''s venturi, and 3. 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!

One important 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 sensors (TPS) provide a(an) _____________voltage signal.

analog

digital

temperature

barometric

Correct! Wrong!

NOx emissions may be reduced by

retarding ignition timing.

lower compression ratios.

use of EGR valves.

all of the above.

Correct! Wrong!

O2 sensors can be contaminated by

leaded fuel.

burning 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. Which one is correct?

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 multi-port fuel injection systems use sequential firing, timed to the engine firing order.

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. Which one is correct?

Technician A

Technician B

both A and B

neither A or 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 system. Which one is correct?

Technician A

Technician B

both A and B

neither A nor B

Correct! Wrong!

To prevent a buildup 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 line 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

speed up.

slow down.

remain at the same speed.

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!

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 fuel injectors.

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!

When someone makes reference to open loop computer control, this means

an input is being sampled to determine how well the system is controlling exhaust gases.

an input is not being sampled to determine how well the system is controlling exhaust gases.

All in puts to the ECM are being sampled to determine how well the system is controlling exhaust gases.

nothing in electronic engine control.

Correct! Wrong!

A gasoline engine''s knock sensor may be

a potentiometer.

rheostat.

a grounding switch.

piezio-electric crystal.

Correct! Wrong!

The PCM can determine the vehicle is in the deceleration mode by which of the following sensors?

Anti-lock brake sensor.

Throttle position sensor.

Canister purge solenoid.

Camshaft position sensor.

Correct! Wrong!

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

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

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

The device 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 runs from the __________ __________ through the metering jets, to the air intake above the carburetor venturi.

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

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 know 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 vacuums created by an engine and carburetor: 1. in the intake manifold below the throttle plates, and 2. in the carburetor''s venturi, and 3. 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?

One important 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 sensors (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. Which one is correct?

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

All multi-port fuel injection systems use sequential firing, timed to the engine firing order.

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. Which one is correct?

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 system. Which one is correct?

To prevent a buildup 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 line 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

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.

When someone makes reference to open loop computer control, this means

A gasoline engine''s knock sensor may be

The PCM can determine the vehicle is in the deceleration mode by which of the following sensors?

Success!

Heavy-Duty Mechanic - Trucks & Equipment

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