Short-cycling means your pump is turning on and off far more often than it should — sometimes every few seconds. It sounds like a small annoyance, but left alone it's one of the fastest ways to wear out a perfectly good pump.
In a healthy system, the pump kicks on when pressure drops to the cut-in setting (often 40 psi) and shuts off once it reaches cut-out (often 60 psi), and stays off until the next real demand for water. A properly charged pressure tank stores enough water in that pressure range to keep the pump off for a reasonable stretch even during normal household use. Short-cycling means the pump is starting and stopping every few seconds instead — sometimes even with no faucet running.
Bladder pressure tanks hold a pocket of compressed air above (or around, depending on design) a water bladder. That air cushion is what lets the tank store usable water across a pressure range. If the tank loses its air charge — through a slow leak at the Schrader valve, age, or a ruptured bladder — the tank can no longer store meaningful water volume, and the pump ends up doing the tank's job: cycling on almost every time there's any demand at all.
Most of the mechanical stress on a pump motor happens during startup — the initial current draw is several times higher than the running current. A pump cycling every few seconds accumulates that startup stress at a rate that can cut years off its expected life, even though the pump itself may be otherwise fine.
If the cause is a lost air charge and the bladder is still intact, recharging the tank can solve it. If the bladder has failed or the tank is undersized, replacement is the more durable fix. Either way, ruling out a leak or a bad check valve first prevents paying to fix the tank only to have the same symptom return.
See our pressure tank service page for what a repair or replacement involves, or call us to get it diagnosed.