FAA Aviation Mechanic Powerplant (AMP)Fuel, Induction and LubricationMedium
A mechanic is comparing carburetor and fuel injection systems on reciprocating engines. Which of the following is a primary advantage of a fuel injection system over a float-type carburetor?
- AFuel injection systems are significantly less expensive to overhaul
- BFuel injection systems do not require a mixture control for altitude compensation
- CFuel injection systems eliminate the need for an engine-driven fuel pump
- DFuel injection systems are much less susceptible to induction icing since fuel is not vaporized in a venturi ahead of the throttle
Show answer & explanationAnswer & explanation
Correct answer: D. Fuel injection systems are much less susceptible to induction icing since fuel is not vaporized in a venturi ahead of the throttle
In fuel injection systems, fuel is injected directly at or near the cylinder intake port rather than being vaporized in a venturi in the induction airstream, greatly reducing susceptibility to carburetor-type induction icing. This is one of the primary safety advantages over carburetor systems.
Why the other options are wrong
- A. Fuel injection systems are generally more complex and expensive to maintain, not less.
- B. Fuel injection systems still require mixture control to compensate for decreasing air density with altitude.
- C. Fuel injection systems still require an engine-driven fuel pump, often at higher pressure than carbureted systems.
Fuel Injection vs Carburetor Icing
Fuel injection systems introduce fuel near the cylinder rather than in a venturi, significantly reducing the risk of induction icing compared to float carburetors.
- Fuel injected near intake port, not in venturi
- Reduces induction icing risk substantially
- Still requires mixture control for altitude
- Requires higher-pressure engine-driven fuel pump
Memory trick: Injection skips the icy venturi, delivering fuel straight to the cylinder's door