Deceleration Valve: Testing and Inspection

Fig. 176 A/B Valve Test:

1. Start and warm the engine to operating temperature.
2. Remove the air cleaner lid and filter.
3. Place your finger over the A/B valve inlet.
4. Run the engine at 3000 RPM and release the throttle quickly.
There should be strong vacuum.
If not proceed to step #5.
5. Check for vacuum leak in A/B source hose.
If no leaks are found replace A/B valve.