Pump stops and starts

About a year ago, we had a new pump put in the well. We have good pressure. If wash machine is running, we cannot use the toilet, do dishes or water outside. Before the pump was replaced, we could run all the water we wanted to. We have changed pressure switch and pressure tank. The party that installed the pump say there is nothing wrong with the pump. Do you have any suggestions? We do not know what else to do.

It sounds like you need to service or replace the pressure tank. You'll get more views if you post this on the pumps and wells section. You need to resolve this, as multiple short-cycling events will quickly ruin the pump.

It sounds as if the gpm is reduced from what the old pump was delivering. It could be he sold you a pump with a smaller gpm or there could be a water leak. You can check for a leak by shutting the water off past the pressure tank and watching the pressure gauge for like 10 minutes to see if the pressure falls. If it does you have a leak between the tank and the check valve of foot valve in the well unless you have a check valve at the tank or the top of the well.

Do you have a submersible or jet pump? If a jet pump you could have a partially blocked jet. If a jet pump, is it one or two lines?

water

Initially, ALL your water comes from the storage tank, until you use enough to start the pump. Therefore, it appears that you have a storage tank, or pressure switch setting, problem.