I have 40 to 60 psi on my pressure gauge and a new pressure tank installed. The issue that I have is that the pressure is good then it drops right off. It will build back up then fall off again. I am not sure what is going on. Please help

Need a little more info.
1. Is your pump is the well or above ground?
2. When you put in a new tank, did you replace the switch?
3. When the pressure "drops right off", do you mean it is a sudden loss of pressure within a few seconds?
4. When your pressure builds back up, is that while you are still using water, or with faucets off?
5. If that is with faucets off, will your pump build pressure while you are still using water?

1. Pump to pressure and turn the pump off. Shut the valve off to the house from the pump.
2. Now open the valve to the house and pump to pressure.
3. Now open the house and watch the gasge.
(1) If. With the line to the house turned off the gage should hold steady. If it doesn't I'd c\check the foot/check valve or perhaps a leak in the suction line,
(2) If the gage holds steady on #1 but falls non #@ you have a leak in the line to the house.
(3) If the gage holds steady on 1 and 2 but fallsn on #3 your problem's in the house. I'd start with the toulets. If you're on a slab you could also have a hidden leak. Let me know what you find and we'll go from 6here. Good luck, Tom

It sounds like the pressure switch is cycling. I would call the plumber back that installed the new tank. Foot valve not working, bladder in tank not pressurized properly, all possibilities.
Shut of main to house. Turn pump on and it should shut off when top end is reached. Shut valve to pump immediately. If pressure stay open valve to house,, pressure may drop a little but not bottom out. If it does drop, something is amiss in the piping in the house. If it stays pressurized, open valve to pump. If it drops , the foot valve is more than likely bad.

Two year old thread.

Which raises an interesting question. People occasionally find "dead" (old) threads on this site and respond to them. How do they find these threads? They have to be buried under hundreds of newer posts. Why pick one several years old?

Not being critical, just absolutely curious.

If one goes to the unanswered questions, or any questions for that matter, there IS no date stamp until that question is pulled up. I know, for myself, I have become interested in answering the question and don't take time to look at the date stamp. Apparently this is not only isolated to myself. I just do not understand why the data base is not purged of questions more than a year old. As I stated earlier, many questions go unanswered, many questions have been answered several times yet they are still here after 5,6,7 years.

Interesting. Thanks for the info.

don't take time to look at the date stamp.

That is the critical part.

Old threads are great for research. Any time a thread gets a new response, it moves to the top of the queue and is shown in bold. That's the way the system works. Please start paying attention.