This set of Automotive Engine Auxiliary Systems Multiple Choice Questions & Answers (MCQs) focuses on “Petrol Engine Fuel Supply System – Carburettor Types”.
1. Which of the following is an example of a constant vacuum type carburetor?
a) Carter carburetor
c) S U carburetor
d) Both Carter and Zenith
Explanation: The S U carburetor is a typical example of variable venturi or constant vacuum type of carburetor. There is both a vertical and horizontal model is being produced. The horizontal type has a spring-loaded piston to control the air passage.
2. Which of the following is an example of constant venturi type carburetor?
a) Zenith carburetor
b) Carter carburetor
c) S U carburetor
d) Both Zenith and Carter carburetor
Explanation: Carter and Zenith type carburetor are the two types of constant venturi. Whereas the S U carburetor is an example for a constant Vaccum type carburetor. Zenith carburetor is one of the most popular carburetors.
3. How many numbers of jets are present in a zenith type carburetor?
Explanation: There are three jets present In a zenith carburetor. The jets are the main jet, compensating jet and the idling jet. The main jet has an outer cover, the annular passage between the main jet and outer cover forms a delivery tube for the compensating jet.
4. Which of the following is a type of arrangement concerning Solex carburetor?
a) Up- drought
c) Down- drought
d) Both Up- droughtand Down- drought
Explanation: Solex carburetor is a down drought type of carburetor, with special provision for a progressive starter which supplies rich mixture for starting and then gradually weakens it till the engine has reached its operating temperature.
5. Which among the following is provided to avoid flat spot during acceleration and delivers spurts of extra fuel in a Solex carburetor?
a) Idle port
b) Membrane pump
c) Idle adjusting screw
Explanation: To avoid flat spot during acceleration a separate membrane pump is provided which delivers spurts of extra needed fuel for acceleration. Pump lever is connected to the accelerator pedal so that when the same is pressed, the lever moves towards left, thus pressing the membrane towards the left and forcing petrol into the main jet.
6. Which of the following helps in the fuel flow when the choke is applied?
a) Main jet
b) Idle jet
c) Transfer port
d) Progression hole
Explanation: When the choke is applied the fuel is made to come out from the main jet and the fuel is delivered. The choke valve is closed, the whole of the engine suction is applied at the main nozzle, which then delivers fuel.
7. Which part of the idling circuit of a carter carburetor the engine suction is applied through which air and fuel are drawn?
a) Low-speed port
b) Main nozzle
c) Idle port
d) Metering rod
Explanation: For idling circuit, the throttle valve is almost closed and the whole engine suction is applied at the idle port, through which the air and the fuel are drawn giving rich mixture. This rich mixture requires more fuel for the proper combustion.
8. Where is the accelerator pedal connected in a full-throttle circuit of a carter carburetor?
a) Idle port
b) Metering rod
d) Inlet valve
Explanation: The metering rod consists of several steps of diameter sizes at its bottom and is connected with the accelerator pedal through linkage. When the accelerator pedal is pressed, the throttle is held wide open and simultaneously the metering rod is lifted.
9. How many way valves are present in a damper plunger of an S U carburetor?
Explanation: The damper plunger has a one-way valve in it. It regulates the rate of lift of piston but allows the same to fall freely when the throttle valve is closed. However the throttle valve is opened suddenly for acceleration, the lifting speed of the piston is retarded by the damper plunger.
10. To adjust which of the following a jet adjusting nut in provided in an S U carburetor?
a) Flow rate
c) Mixture strength
Explanation: The jet adjusting nut is meant to adjust mixture strength. Tightening the nut will raise the jet, thereby reducing the annular area for fuel flow. Similarly loosening the nut powers the jet and thus increases the fuel supply which is getting delivered to the engine.
11. Which of the following is the main advantage of drought type carburetor?
a) High volumetric efficiency
c) Defective float
d) Jet overflowing
Explanation: The drought type is most widely used as it has high volumetric efficiency, gravity assist for the flow,etc. Whereas the leakage, defective float, and jet overflowing are the sign of a bad carburetor which is not desired.
12. Inside which of the following is the lower end of the needle placed in an S U carburetor?
Explanation: The piston moves up and down, the needle also moves up and down .the lower end of the needle is inside the main jet. The up and down movement of the tapering needle causes the annular area for fuel flow to increase or decrease.
13. During which of the following the mixture tends to become richer in a single jet carburetor?
a) During winter
b) At low altitude
c) At high altitude
d) During idling
Explanation: At high altitudes, the mixture tends to become richer in a single jet carburetor as there is no supply of air at higher altitudes due to which the engine will have more fuel consumption when compared to an engine at sea level.
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