Fuel Systems & Combustion Flashcards
6 cards from real Automotive and Mechanics practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 6 Fuel Systems & Combustion flashcards as text
What is the stoichiometric air-fuel ratio for gasoline engines?
Answer: 14.7:1
The stoichiometric air-fuel ratio for gasoline is 14.7:1, meaning 14.7 parts air to 1 part fuel for complete combustion.
Which fuel system component regulates fuel pressure delivered to the injectors?
Answer: Fuel pressure regulator
The fuel pressure regulator maintains consistent fuel pressure to the injectors, typically between 35–65 psi depending on the system.
What causes a rich air-fuel mixture condition in a fuel-injected engine?
Answer: Faulty MAF sensor reading high
A MAF sensor reading higher than actual airflow causes the ECU to inject excess fuel, creating a rich mixture.
What is the purpose of a returnless fuel system?
Answer: Keeps fuel in the tank cooler by not returning hot fuel
Returnless fuel systems keep hot fuel from cycling back to the tank, reducing vapor lock and evaporative emissions.
Which type of fuel injection sprays fuel directly into the combustion chamber?
Answer: Direct injection
Direct injection (GDI) sprays fuel directly into the combustion chamber at high pressure, improving efficiency and power.
What does a knock sensor detect in an engine?
Answer: Abnormal combustion (detonation)
A knock sensor detects detonation or pre-ignition vibrations and signals the ECU to retard ignition timing.