Vacuum Control Valve

Fig. 29 - Vacuum Control Valve Test:

1. Disconnect and plug intake manifold vacuum hose from anti-afterburn valve at the tee fitting. Connect a vacuum gauge to the tee fitting, Fig. 29.

2. Start engine and raise speed to 3000 RPM, then release accelerator and observe vacuum gauge. The vacuum reading should drop to 22.4 inch Hg. momentarily before dropping to the normal idle vacuum reading.

3. If the vacuum reading is not within specifications, loosen locking screw and rotate adjusting screw on vacuum control valve until the proper reading is obtained.

NOTE: The vacuum level at which the vacuum control valve operates was set at an atmospheric pressure of 22.9 inch Hg. If the atmospheric pressure at time of testing is different than 22.9 inch Hg., change the desired reading by adding or subtracting the amount equivalent to the difference between 22.9 inch Hg. and the actual atmospheric reading.