ASVAB Automotive Information Practice Test 422027

Questions 5
Topics Air-Fuel Mixture, Crankshaft, Electric Fuel Pump, Lighting, Master Cylinder

Study Guide

Air-Fuel Mixture

The stoichiometric ratio defines the proper ratio of air to fuel necessary so that an engine burns all fuel with no excess air. For gasoline fuel, the stoichiometric ratio is about 14.7:1 or for every one gram of fuel, 14.7 grams of air are required. Too much air results in a lean air-fuel mixture that burns more slowly and hotter while too much fuel results in a rich mixture that burns quicker and cooler.


The crankshaft converts the reciprocating motion of the piston into the rotational motion that's used to power the vehicle and its components.

Electric Fuel Pump

The electric fuel pump feeds pressurized fuel through a fuel filter to the fuel injectors via the fuel rail manifold. The fuel rail contains the fuel pressure regulator which ensures that the fuel injectors receive fuel at a consistent and known rate. Excess fuel bled off by the pressure regulator returns to the fuel tank through the fuel return line.


The lighting system consists of interior lights, instrument panel lighting, headlights, and taillights. Like household electrical circuits, the vehicle's lighting system is protected from current spikes by fuses and circuit breakers.

Master Cylinder

The master (brake) cylinder converts pressure on the brake pedal to hydraulic pressure in the brake lines.