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Carburetor Systems

 Carburetor Systems

  • To provide for engine operation under various loads and at
  • different engine speeds, each carburetor has six systems:
  • 1. Main metering
  • 2. Idling
  • 3. Accelerating
  • 4. Mixture control
  • 5. Idle cutoff
  • 6. Power enrichment or economizer
  • Each of these systems has a definite function. It may act alone or with one or more of the others.
  • The main metering system supplies fuel to the engine at all speeds above idling.
  •  The fuel discharged by this system is determined by the drop in pressure in the venturi throat.
  • A separate system is necessary for idling because the main metering system can be erratic at very low engine speeds.
  • At low speeds, the throttle is nearly closed.
  • As a result, the velocity of the air through the venturi is low and there is little drop in pressure.
  • Consequently, the differential pressure is not sufficient to operate the main metering system, and no fuel is discharged from this system.
  •  Therefore, most carburetors have an idling system to supply fuel to the engine at low
  • engine speeds.

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