Diagnosis
That's the automatic tank-fill function, but it's cycling way too often. It usually means there's a slow leak of pressure, either from a check valve issue or a leaking tank bladder.
How to Fix It
First, check the tank's air pressure. Shut off the system, open the faucet to drain the tank completely, then check the air valve on the tank (it looks like a bike tire valve). It should read around 7-8 PSI when empty. If it's low, use a bicycle pump to bring it back up.
If That Didn't Work
The internal check valve (inside the manifold) might be failing, letting water slowly creep back from the tank into the membrane housing, causing the pressure to drop and the pump to kick on to compensate.
Heads Up
Frequent, short cycles are hard on the pump. If adjusting the tank pressure doesn't solve it, the check valve is likely the culprit and needs replacement.