Automotive Engine Auxiliary Systems Multiple Choice Questions on “Petrol Engine Fuel Supply System – Simple Carburettor”.
1. Which of the following material is used to make the float of a carburetor?
a) Paper
b) Sheet metal
c) Nylon plastic
d) Cast iron
Answer: b
Clarification: The floats have a tendency to leak along the joint seams.due to which they are made of nylon plastic or expanded synthetic rubber. The needle valve attached to the float serves to close or open the fuel inlet to the float chamber depending on the requirements.
2. Which of the following is provided in the float chamber to keep the pressure inside atmospheric?
a) Float
b) Fuel jet
c) Small vent
d) Throttle valve
Answer: c
Clarification: A small vent in the float chamber keeps the pressure inside the atmospheric. In modern practice, it is preferred to vent the float chamber to the air intake of the carburetor. In modern practice, it is preferred to vent the float chamber to the air intake of the carburetor.
3. Which of the following increases with the reduction of area in a venturi?
a) Temperature
b) Velocity
c) Enthalpy
d) Entropy
Answer: b
Clarification: In the venturi the passage is is minimum. Thus due to less area, the air velocity increases and because of this increase in velocity, a decrease in pressure is caused at the nozzle which is located in venturi itself.
4. Which among the following does not affect the amount of fuel delivered?
a) Jet size
b) Float level
c) Venturi vacuum
d) Ignition timing
Answer: d
Clarification: The amount of fuel delivered depends upon the major factors like jet size, float level, and venturi vacuum. Whereas the ignition timing does not affect the amount of fuel that is being delivered to the engine via the carburetor.
5. What is the main function of a throttle valve?
a) Temperature
b) Air-fuel
c) Enthalpy
d) Entropy
Answer: b
Clarification: The purpose of a throttle valve is to control the quantity of the air-fuel mixture and it is attached to the accelerator pedal. Whereas there is no such great effect of the throttle valve in the factors like temperature, enthalpy, and entropy.
6. Which of the following component is used to maintain the liquid-tight seal during vibration?
a) Three-piece valve with rubber seat tip
b) Vent
c) Nozzle
d) Throttle valve
Answer: a
Clarification: A three-piece valve with a rubber seat tip and a spring-loaded ball In the body of the stem. Whereas the other components like the vent, nozzle and the throttle valve are the main parts of a carburetor which helps in the air-fuel mixture ratio.
7. What is the main function of a float in the float chamber?
a) Constant head of fuel
b) Ventilation
c) Temperature control
d) Enthalpy
Answer: a
Clarification: The fuel starts to flow in and the float rises gradually till the fuel level reaches the desired value. At this time, the float needle closes the fuel inlet passage. Thus a constant head of fuel is maintained in the float.
8. In practice what is the fuel level in the float chamber that is maintained in millimeter below the nozzle?
a) 10
b) 5
c) 20
d) 15