Small Engine Tech-Carburetor Quiz

Questions and Answers

A governor malfunction that results in engine speed oscillations is known as ____________.

hunting

A carburetor relies on ____________________ in pressure to mix fuel and air and to keep the mixture moving in the right direction.

differences

What is a reservoir containing extra fuel that is drawn into the airstream when the throttle valve is suddenly opened?

acceleration well

What part of the carburetor increases the speed of airflow and decreases pressure?

venturi Signup and view all the answers

At normal engine speed under normal operating conditions, the proper air-fuel mixture ratio is typically ________ parts air to 1 part fuel.

15 Signup and view all the answers

The carburetor causes fuel to flow through the main nozzle into the airstream; lowers the boiling point of the fuel, causing some of the fuel to vaporize before it reaches the cylinder; and increases the speed of the airstream, atomizing the fuel leaving the main nozzle when there is a _ __.

pressure reduction Signup and view all the answers

What are the three groups carburetors can be categorized into, based on the airflow through the air horn?

natural draft, updraft, downdraft Signup and view all the answers

What part of the carburetor is responsible for maintaining a constant fuel level in the float bowl?

float Signup and view all the answers

If the float springs a leak or becomes saturated and sinks, too much __________ will be provided to the engine.

gas Signup and view all the answers

The purpose of the ____________ is to provide a rich mixture for cold engine starting.

choke Signup and view all the answers

When the throttle valve is completely closed in a natural draft carburetor, most fuel is provided to the engine through the __________ _ __________.

primary idle orifice Signup and view all the answers

What kind of carburetor has an integral impulse fuel pump?

diaphragm Signup and view all the answers

What kind of carburetor is always mounted on top of the fuel tank?

vacuum Signup and view all the answers

These primers increase air pressure in the float bowl, forcing fuel up the main nozzle.

dry bulb Signup and view all the answers

As engine load decreases and engine speed increases, a governor with __________ the throttle.

close Signup and view all the answers

What type of governor adjusts engine speed based on the movement of flyweights on the governor gear?

centrifugal Signup and view all the answers

Vacuum governors are located between the carburetor and the _ ____.

intake manifold Signup and view all the answers

In an EFI system, what does the MAP sensor send information about?

intake airflow Signup and view all the answers

The IAT sensor improves the efficiency of a fuel injection system because it sends a signal to the ECU that allows the ECU to make adjustments to the fuel mixture based on ____________.

air temperature Signup and view all the answers

This sensor is used only in closed-loop EFI systems, monitors the chemical composition of exhaust gases, and provides feedback to the ECU that is used to adjust fuel trim.

O2 Signup and view all the answers

Delivers fuel to the venturi when the engine is operating at speeds above idle.

main discharge nozzle Signup and view all the answers

What restricts airflow into the carburetor to enrich the air-fuel mixture?

choke system Signup and view all the answers

What reduces air pressure in the float bowl when the engine is operating at part throttle?

economizer circuit Signup and view all the answers

What regulates the amount of air-fuel mixture entering the cylinder?

throttle system Signup and view all the answers

What increases air velocity and reduces pressure by restricting the carburetor's air passage?

venturi Signup and view all the answers

What maintains a constant fuel level within the carburetor?

float system Signup and view all the answers

What provides additional fuel when airflow through the carburetor is maximized?

acceleration system Signup and view all the answers

What delivers a small amount of air-fuel mixture to the cylinder when the throttle valve is closed?

idling system Signup and view all the answers

Study Notes

Carburetor Terminology

Hunting refers to engine speed oscillations caused by a governor malfunction.
A carburetor relies on differences in pressure to mix fuel and air appropriately.
The acceleration well is a reservoir that provides extra fuel when the throttle valve opens suddenly.
The venturi section of a carburetor accelerates airflow while decreasing pressure.

Fuel-Air Mixture

The ideal air-fuel mixture ratio at normal engine speed is typically 15 parts air to 1 part fuel.
Fuel vaporization is enhanced by pressure reduction in the carburetor, allowing better atomization.

Carburetor Types

Carburetors can be grouped by airflow type: natural draft, updraft, and downdraft.

Carburetor Components

The float maintains a constant fuel level in the float bowl; a malfunction can lead to excessive gas delivery.
Choke mechanisms enrich the fuel mixture for cold starts.
The primary idle orifice supplies fuel when the throttle valve is closed in a natural draft carburetor.
Diaphragm carburetors have an impulse fuel pump integrated within.

Engine Management

Vacuum carburetors are typically placed atop the fuel tank.
Dry bulb primers function by increasing air pressure in the float bowl, pushing fuel into the main nozzle.
Governors operate by adjusting the throttle as engine load and speed change.

Sensors and Fuel Injection

The MAP sensor in EFI systems monitors intake airflow and relays data to the ECU.
The IAT sensor adjusts fuel mixtures based on air temperature, improving EFI efficiency.
The O2 sensor in closed-loop EFI systems provides feedback on exhaust gas composition to adjust fuel trim.

Fuel Delivery Systems

The main discharge nozzle delivers fuel to the venturi during high engine speeds.
The choke system limits airflow to create a richer air-fuel mixture.
The economizer circuit reduces float bowl pressure during part throttle operation.
The throttle system manages the air-fuel mixture entering the engine's cylinders.

Additional Systems

The float system ensures a stable fuel level in the carburetor.
The acceleration system provides extra fuel under maximum airflow conditions.
The idling system maintains a consistent air-fuel mixture when the throttle valve is closed.

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Description

Test your knowledge on carburetor functions and terminology with this quiz. Each question is designed to help reinforce your understanding of key concepts important in small engine technology. Ideal for students and enthusiasts alike.