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 is the primary function of an accelerator pump in a float-type carburetor?
Answer: Provide extra fuel during rapid throttle opening to prevent a lean mixture
The accelerator pump delivers an extra shot of fuel when the throttle is opened quickly, preventing a momentary lean mixture that could cause engine stumble.
In a pressure-injected carburetor, the fuel control unit meters fuel based primarily on which parameter?
Answer: The differential pressure between impact air and venturi suction
Pressure-injected carburetors use the differential between impact (ram) air pressure and venturi suction to meter fuel flow proportional to airflow.
Which component in a continuous-flow fuel injection system controls fuel distribution to individual cylinders?
Answer: Flow divider (fuel manifold valve)
The flow divider (manifold valve) receives metered fuel from the fuel control unit and distributes it equally to each cylinder's injector nozzle.
What is the purpose of the idle cut-off position on a mixture control?
Answer: Stop fuel flow to shut down the engine cleanly
Moving the mixture control to idle cut-off stops fuel flow to the engine, allowing shutdown by fuel starvation rather than ignition cutoff, which burns residual fuel and prevents after-firing.
A carburetor's economizer system (power enrichment valve) is designed to:
Answer: Enrich the mixture at high power settings to prevent detonation and overheating
The economizer (power enrichment valve) opens at high power settings to richen the mixture, providing cooling and preventing detonation.
In an RSA fuel injection system, the fuel control unit is driven by:
Answer: Airflow through the throttle body, sensed by an air diaphragm
The RSA injector's air diaphragm senses airflow by measuring the pressure differential across the throttle body and uses it to position the metering valve.
When troubleshooting a float-type carburetor that floods excessively, the FIRST item to inspect is:
Answer: Float level and needle valve for wear or contamination
Flooding is most commonly caused by a float set too high, a leaking float, or a contaminated/worn needle valve that fails to seat properly.