FAA Aviation Mechanic Powerplant (AMP)Fuel, Induction and LubricationEasy
A mechanic is adjusting the float level on a float-type carburetor during overhaul. If the float level is set too high, what is the most likely result during engine operation?
- AThe mixture will be too lean at all power settings
- BThe engine will be starved for fuel at high power
- CThe fuel level in the discharge nozzle will be too high, causing a rich mixture and possible flooding
- DThe float will stick in the open position, preventing engine start
Show answer & explanationAnswer & explanation
Correct answer: C. The fuel level in the discharge nozzle will be too high, causing a rich mixture and possible flooding
Float level determines the fuel level maintained in the carburetor bowl relative to the discharge nozzle. A high float level raises the fuel level, increasing fuel flow through the nozzle and causing an overly rich mixture or flooding.
Why the other options are wrong
- A. Opposite effect; a high float level causes richness, not leanness.
- B. Fuel starvation is associated with a low float level, not a high one.
- D. Float sticking is a mechanical defect unrelated to level adjustment.
Float Level Adjustment
The float level sets the fuel height maintained in the carburetor bowl, which controls fuel delivery through the discharge nozzle.
- Float level is set per manufacturer specs using a float gauge
- High float level = rich mixture/flooding
- Low float level = lean mixture/fuel starvation at high power
Memory trick: Float high, fuel flies high (too rich)