Deceleration Valve: Testing and Inspection

Fig. 56 Removing The #6 Vacuum Hose From The Throttle Controller:

1. Start the engine and warm up to normal operating temperature (cooling fan should cycle ON and OFF at least once).
2. Disconnect the #6 vacuum hose from the throttle controller and check the idle speed, Fig. 56. Idle speed should be:

Manual transmission .......... 2200 +/- 500 rpm
Automatic Transmission ....... 1900 +/- 500 rpm (in "N" or "P")

Fig. 57 Throttle Controller Adjustment Tab:

3. If the engine speed is excessively high, adjust the engine speed by bending the tab, Fig. 057.

Fig. 58 Checking For Vacuum To The Throttle Controller:

4. If the engine speed does not change when the vacuum hose is removed, connect a vacuum gauge to the #6 vacuum hose. With the engine idling, vacuum should be available.
a. If there is no vacuum, check the #6 vacuum hose for proper connection, cracks, blockage, or disconnection, and replace the check valve, Fig. 58.
b. If vacuum is available, replace the throttle controller and re-test.
5. Reconnect vacuum hose #6 and check the idle speed. Idle speed should be:

Manual Transmission .......... 800 +/- 50 rpm
Automatic Transmission ....... 750 +/- 50 rpm (in a drive gear)