Mechanical Inspection: Vacuum

Engine vacuum that is developed in intake line is a good indicator of engine condition. Perform engine vacuum check as follow:

1. Set transmission shifter lever in "Neutral" position ("P" range for A/T model), set parking brake and block drive wheels. Start engine and allow it to reach normal operating temperature. Ensure that engine idle speed is within specification. See IDLE SPEED & MIXTURE in ON-VEHICLE ADJUSTMENT article.
2. Turn ignition switch to LOCK position. Disconnect vacuum hose and connect vacuum gauge and 3-way joint hose between vacuum hose and intake manifold (Aerio and Vitara). See Fig 1 . Disconnect vacuum hose and connect vacuum gauge and 3-way joint hose between vacuum hose and fuel pressure regulator valve (Grand Vitara and XL-7). See Fig 1 .
3. Start engine and let it idle. Read vacuum gauge, vacuum should be within specification. See VACUUM SPECIFICATION  table. If vacuum is not as specified, check engine compression. See COMPRESSION  . Also check exhaust backpressure. See EXHAUST SYSTEM BACKPRESSURE  .

Fig 1: Installing Vacuum Gauge

Courtesy of SUZUKI OF AMERICA CORP.