DR-26B Checking EGR Back Pressure Valve

1. With engine running, disconnect vacuum line from EGR valve.
2. Connect a vacuum gauge to disconnected EGR vacuum line, then raise engine speed to 2000 RPM.
3. If vacuum gauge shows 1 to 5 inches of vacuum, proceed to Test 27.
4. If vacuum gauge shows vacuum above 5 inches of vacuum, replace EGR back pressure valve.
5. If vacuum gauge indicates no vacuum, proceed to Test 26 step C.