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Questions and Answers
The fuel metering orifice draws fuel from the ______ chamber
float
The passage leading to the ______ system is one of the principal units of the main metering system
idling
The main metering system has three functions, one of which is to ______ the fuel-air mixture
proportion
The main metering system also ______ the pressure at the discharge nozzle exit
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At full throttle, the main metering system ______ the air flow
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The choke valve is used to provide a rich mixture to initiate combustion at low temperatures, typically during ______ winter seasons
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The gasoline is filtered by installing a ______ at the inlet to the float chamber.
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The function of a ______ in a carburetor is to supply the fuel to the nozzle at a constant pressure head.
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The ______ and throttle are used to control the air-fuel mixture during different engine conditions.
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The main ______ and idling nozzles are responsible for providing the correct air-fuel mixture during engine operation.
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The float in a carburetor is designed to control the level of ______ in the float chamber.
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The correct amount of ______ flow is provided by maintaining a constant level of fuel in the float chamber.
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When the throttle valve is closed or nearly closed, the manifold vacuum created behind the throttle is sufficient to pull a small amount of fuel and air through small openings located after the butterfly valve, this is called the ______ circuit.
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The ______ circuit provides extra fuel at high load levels to produce maximum power.
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The main metering system of the carburetor controls the fuel feed for ______ and full throttle operations.
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The accelerator pump ______ helps to provide additional fuel during acceleration.
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The ______ circuit is responsible for providing fuel for full power operations.
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The main ______ circuit of the carburetor controls the fuel feed for cruising and full throttle operations.
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Study Notes
Carburetor Components
- The carburetor consists of three principal units: fuel metering orifice, main discharge nozzle, and passage leading to the idling system.
Main Metering System
- The three functions of the main metering system are:
- to proportion the fuel-air mixture
- to decrease the pressure at the discharge nozzle exit
- to limit the air flow at full throttle
Choke and Throttle
- A choke valve is used to provide a very rich mixture (as rich as 9:1) for initiating combustion in cold weather conditions.
- At low cranking speeds and intake temperatures, a rich mixture is required because the fuel may remain as liquid suspended in air even in the cylinder.
Fuel Strainer
- A fuel strainer is installed at the inlet to the float chamber to filter gasoline and prevent nozzle blockage by dust particles.
Float Chamber
- The function of a float chamber is to supply fuel to the nozzle at a constant pressure head.
- The fuel level in the float bowl must be maintained slightly below the discharge nozzle outlet holes to provide the correct amount of fuel flow and prevent leakage.
Circuits
- The choke circuit provides a rich mixture for starting the engine in cold weather conditions.
- The idle circuit enables the engine to keep running when the throttle valve is closed or nearly closed.
- The off-idle circuit provides additional fuel when the throttle valve is slightly open.
- The power circuit provides extra fuel at high load levels when engine vacuum drops below a pre-set level.
- The main metering circuit controls fuel feed for cruising and full throttle operations.
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Description
This quiz covers various circuits in an automobile fuel system, including the full power circuit, accelerator pump circuit, choke circuit, and idle & off-idle circuit. Learn how these circuits work together to provide the correct air-fuel mixture to the engine.
