Carburetor and fuel injection

How a float-type carburetor meters fuel, why it ices in warm weather, and how fuel injection differs.

12 min read · The airplane: engine and systems

After this lesson you can

  • Explain how the venturi in a float-type carburetor draws fuel into the airstream.
  • State the temperature and humidity conditions under which carburetor icing is most likely, and explain why it can occur even on a warm day.
  • Recognize the first symptom of carburetor icing on both fixed-pitch and constant-speed installations, and apply carburetor heat correctly.
  • Explain why fuel injection reduces, but does not eliminate, the risk of induction icing.

Carburetor icing is one of the strange failures in aviation: it can happen on a clear, warm afternoon, it gives almost no warning beyond a slowly dropping engine indication, and it remains one of the few engine problems a pilot can prevent entirely just by understanding when to expect it.

This lesson covers how the float-type carburetor meters fuel, why that mechanism is inherently prone to icing, and how the alternative -- fuel injection -- trades that vulnerability for a different set of quirks.

The rest of this lesson

  1. 1.How a float-type carburetor works
  2. 2.Why carburetor ice forms
  3. 3.Recognizing it in the cockpit
  4. 4.Using carburetor heat
  5. 5.Fuel injection
  6. 6.The carburetor air temperature gauge

These 6 sections, their figures, the checks along the way and the end-of-lesson quiz come with the PPL track. Paid once, yours for good.

See what the PPL track costsEvery module 1 is free to read, no account, no card.

Key terms

Try to recall each definition before turning the card.