My well pump kicks on and off constantly when no water is running. Pressure builds up to normal cut off pressure and drops right back down to cut in pressure causing the pump to kick on every 30 seconds. Could my pressure switch cause this or is my pressure tank leaking.

My bet's on a faulty check/foot valve.
Yhis is the fitting that keeps the pressure in your system. If it's bad the pressure will bleed back into the nwell and your pump will start to build it back up only to have it start all over again. Replace the check/foot valve. Good luck, Tom

I think SB has nailed it. This site will be useful for you:

Water system check valve location & purpose - private pump and well system do-it-yourself repairs

I just had the same problem. The pump would cycle every five seconds with no water flowing and no leaks. I suspected the check valve so I pulled the pump from the ground (casing). My pump has a built in valve that is not replaceable so I added a valve inline with the pumps outlet just above the outlet. Couldn't see spending $400 on a new pump just to replace the valve. The valve and nipple were about $20 including hose clamps and teflon tape. This fixed the problem. A few days later the pump started to cycle rapidly again but this time only when using/calling for water. I found the pressure tank to be full of water providing no buffering. The bladder inside must have failed and choked off the outlet because when I disconnected the tank no water came out. A new pressure tank fixed this problem. I did also purchase a new pressure switch because I am sure the contacts are worn from all the cycling. Will install soon.
Hope this helps
Mark

My pump keeps trying to turn on and off -all day even with no water running I have already replaced the switch box on the pump and it's still doing the same thing thank you in advance