B2 - Vacuum Test

^ Attach vacuum gauge to intake manifold vacuum source.

^ Hook up tachometer.

^ While observing the vacuum gauge needle, START the engine and gradually increase the engine speed to 2000 rpm with the transmission in neutral.

NOTE: The vacuum gauge reading may be normal when the engine is first started and idled. However, excessive restriction in the exhaust system will cause the vacuum gauge needle to drop to a low point even while the engine is idled.

^ Decrease engine speed to base idle rpm.

^ Did manifold vacuum reach above 16 inches of mercury with the engine rpm at 2000?


YES -- No restriction in the exhaust system. Refer to lack of power. SEE Powertrain Management / Testing and Inspection / Diagnostic Routines / Lack of Power.

NO -- Go to B3. B3 - Vacuum Test -- Rate of Vacuum Gauge Needle Return Movement