This video is posted as part of troubleshooting a Generac Guardian 4456-2. The unit was installed in 2004 and has around 600 hundred hours. It started surging as shown, and the incoming pressure was fluctuating significantly between 10 and 13 inches of water. Will update description when cause is determined.
Follow-up: This problem was cured by using the Speed No Load adjustment on page 13 of the owner's manual. This screw is located next to the dipstick on this model.
