Engine Fuel Metering Systems Flashcards
7 cards from real AMT practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Engine Fuel Metering Systems flashcards as text
What effect does carburetor ice formation have on engine operation?
Answer: Causes a progressive loss of engine power due to reduced airflow and mixture enrichment
Carburetor ice forms in the venturi throat, restricting airflow and progressively richening the mixture, causing a loss of power that worsens if untreated.
In a fuel injection system, what is the result of a clogged injector nozzle on the affected cylinder?
Answer: That cylinder will run lean, potentially causing overheating or misfiring
A clogged injector restricts fuel to that cylinder, creating a lean condition that can cause overheating, rough running, or detonation.
The fuel-air mixture control in a float carburetor changes the mixture by:
Answer: Moving a needle or plate that restricts the fuel passage in the main discharge circuit
The mixture control needle or plate restricts or blocks the passage between the float chamber and the main discharge nozzle to lean or richen the mixture.
Which type of carburetor system is LEAST susceptible to carburetor ice because the fuel-air mixing does not occur in the venturi?
Answer: Direct fuel injection system
Direct fuel injection introduces fuel at each cylinder intake port rather than in a venturi, so the cooling and ice-forming conditions present in carburetors do not occur.
An automatic mixture control (AMC) in a carburetor compensates for altitude by:
Answer: Using an aneroid bellows to lean the mixture as air density decreases with altitude
The AMC uses an aneroid bellows that expands as ambient pressure decreases, mechanically leaning the mixture to maintain the correct fuel-air ratio with altitude.
What would a fuel flow gauge reading significantly HIGHER than normal on a fuel-injected engine most likely indicate?
Answer: A stuck-open flow divider valve
A stuck-open flow divider can cause abnormally high fuel flow indications and rich running because fuel bypasses metering and floods the distribution system.
During a ground run-up, a carburetor heat check should produce:
Answer: An initial drop in RPM, possibly followed by a slight increase if ice was present
Applying carb heat introduces warmer, less dense air causing an RPM drop; if ice was present, the RPM may recover slightly as the ice melts and airflow improves.