A vacuum gauge is being used to check for a restricted exhaust system. The vacuum at idle is 18 in. Hg. Which of these results indicates a restriction?
A) Vacuum at 2,500 RPM is 22 in. Hg.
B) Vacuum at 2,500 RPM is 19 in. Hg.
C) Vacuum at 2,500 RPM is 9 in. Hg.
D) Not enough information to diagnose

Question

Quizplus · Accepted Answer

A restricted exhaust system will cause a drop in vacuum as the engine RPM increases. Option C shows a significant drop in vacuum, indicating a restricted exhaust system. Option A shows an increase in vacuum, which is unlikely with a restricted exhaust system, and option B shows a minor drop in vacuum, which may be within normal limits. Option D cannot be chosen as there is enough information provided to diagnose.

A Vacuum Gauge Is Being Used to Check for a Restricted