Vacuum Control Systems

TSB #49 - November 4, 1966

If excessive leak-down is suspected, it can be checked by inserting an appropriate "T" fitting at the center nipple of the affected vacuum reservoir (See TSB #46) and connecting the Rotunda Fuel Pump Tester Gauge (ARE-345) to the "T".

It is important to be sure that the gauge hose has tight connections at both ends.

Set all headlight, door lock, heater and/or Air Conditioning controls to the "off" position.

Start the engine and run until vacuum reading stabilizes.

Shut off engine and observe vacuum gauge reading for a period of one minute. If there is no perceptible drop in vacuum reading during this period, the leak-down characteristics of the system are acceptable.

The Illus. S1127-A shows the connections and the appropriate type of "T" connection to be used for this test.