Question

air leaks in the induction system can be tested by all of the following methods except:

a. using a substitute fuel to artificially enrich the mixture at the point of the leak
b. using a smoke machine to fill the intake system and show any external leaks.
c. using an electronic stethoscope to listen for and pinpoint the source of the leak
d. submerging the system in water and looking for air bubbles.

Explanation:

• Option a: Using a substitute fuel to enrich the mixture at the leak point can help detect leaks as it affects the combustion mixture.
• Option b: A smoke machine filling the intake system can visually show external leaks as smoke will escape from the leak points.
• Option c: An electronic stethoscope can listen for the hissing sound of air escaping and pinpoint the leak source.
• Option d: Submerging the induction system (which is part of the engine's air - intake, not a watertight component like a fuel tank or a simple container) in water is not a practical or safe method. The induction system has components that are not designed to be submerged, and water can cause damage to sensors, electrical components, and the engine itself.

Answer:

d. Submerging the system in water and looking for air bubbles.