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First step before removing a carburetor

Aviation Mechanic Powerplant (AMP) practice question 13 of 20 on Engine Fuel and Fuel Metering Systems. ACS element AM.III.I.R2 · difficulty: recall. Want to answer it in a timed quiz? Use the Aviation Mechanic Powerplant (AMP) practice mode.

Question bank updated 2026-09-22

QUESTIONWhat must be done before a carburetor is removed from an engine?

  1. ADrain all of the aircraft fuel tanks completely
  2. BClose the fuel shutoff or selector valve
  3. COpen the throttle valve fully
Show the answer and explanation

Correct answer: B. Close the fuel shutoff or selector valve

  • A — incorrect Draining the tanks is not part of the removal procedure; isolating the carburetor with the shutoff or selector valve is what stops the fuel supply.
  • B — correct The removal procedure begins with making sure the fuel shutoff or selector valve is closed, so that fuel is not delivered to the unit being disconnected.
  • C — incorrect The throttle valve is lockwired in the closed position during removal, not opened, so that nothing enters the induction passages.

BACKGROUND

Carburetor removal procedures vary with the type of carburetor and the engine it is used on, so the manufacturer's technical instructions always govern, but the general sequence is much the same. Before removing a carburetor, make sure the fuel shutoff or selector valve is closed. The throttle and mixture control linkages are then disconnected and the throttle valve is lockwired in the closed position, and the fuel inlet line and all vapor return, gauge, and primer lines are disconnected. If the same carburetor is to be reinstalled, the rigging of the throttle and mixture controls is not altered. Where there is danger of foreign material entering open fuel lines during removal or installation, the lines are plugged with the proper cover fittings.

STUDY TIP

Fix the order in mind: shut off the fuel first, then disconnect linkages and lines, then plug what you opened. The shutoff valve is what keeps the disconnected inlet line from continuing to feed fuel.

KEY POINTS

  • Close the fuel shutoff or selector valve before removing a carburetor.
  • Lockwire the throttle valve closed and disconnect the inlet, vapor return, gauge, and primer lines.
  • Plug open fuel lines with proper cover fittings when foreign material could enter.

SOURCES

  • amp-powerplant/ch02.txt "Carburetor Removal"
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MORE ON ENGINE FUEL AND FUEL METERING SYSTEMS

SkyDrill is not affiliated with the FAA. This is an original practice item based on FAA-H-8083-32B Aviation Maintenance Technician Handbook – Powerplant, and 14 CFR part 43. Regulations and handbooks are revised; confirm details against the current edition.