The infrastructure:
42 Gal pressure tank (16 years old)
Square D Pressure Switch (>1 yr old)
Private well - new about 10 years ago

Both units are in the same house - unit #2 is an addition to unit#1. the split in the feed for both is outside of the house.

-----unit #2--valve---use
Well --|
-----unit #1---Presure switch--presure tank--valve---use

The problem:
On use (flushing toilet) the pressure switch kicks in right away
On constant use (garden spinkler) the pressure continues to fall into the low 30's even as the pump is on.
When the water is turned off - the recovery of pressure is slow until it gets to just over 40 lbs & then it is rapid until it gets to it's cut off (60 lbs).
The pressure holds at max when the feed to both units is shut at valves displayed above

I have been unable to find definitive advice as there is ay least one aspect in the diagnosis of everything suggested so far that fails to fit this situation.

Any ideas of what I can do or where I should look?

Thank you,
ebfisher3

My guess would be,
1. A leaking or ruptured bladder resulting in a water logged tank.
And
2. A defective multistage pump, first stage being defective and second stage kicking in at 40 lbs.

Drain tank and check for proper air charge. Observe operation. Work around for pump might be to reset pump cut-in and cut-out to 40-60 lbs.

Thanks for the fast response. I really appreciate it.

I have reset the ci-co pressure as indicated. I'll work on the tank next.

Empty, the tank has a pressure of about 17lbs. I figure this should be quite a bit higher.

That pressure should be 2# BELOW your cut in pressure. So, if the CI pressure is 30#, then you would set the tank to 28#.

Is this a submerged pump?

I have filled the empty tank air pressure to about 38lbs, the cip to about 40 lbs, & the cop to about 60 lbs.

It now takes A LOT LONGER to get up to the cop and it takes longer to get to the cip, but I still seem to over-run the capacity of the system. When I run the lawn sprinkler and washing machine at the same time the pressure drops to about 37 lbs.

This is a submerged pump. I think that the well is over 200' deep. (my first well was 140' and full of iron - the new well is about 10 years old).

Apparently my diagnosis of multi stage pump was incorrect. Reset pump to 30-50, lower empty tank pressure to 28lbs. See what happens. It may be that pump is defective and can not over ride depth of well and pressure in tank. Does one flush of toilet still make pump come on. What size tank do you have?

42Gal tank - It's 11 pm here now & I just got home - I'll set it per your recommendations tomorrow.

When you open the air valve on top of the tank does water come out? Regards, Tom

Personally, I would leave it at 40-60, even though it will pump less water volume at the higher pressure. I would just restrict how much water you are using... not use the irrigation with the washer. Of course if it is too drastic to where somebody can't use the sink and the shower at the same time, that isn't good. In that case, you can lower the pressure to see if that does the trick.

If you do lower pressure, don't be surprised if you experience the same thing in a few weeks or months. Usually if I have to lower the pressure on a customer's pump, it is just a temporary measure to get them by until they have the money to replace it. Think about it, if it ran before at the pressure and it doesn't now, something is wrong. Usually just wear. Sometimes pipe has holes in it down in the well.
Al

Al,
Note the rapid increase in pressure after reaching 40 lbs in the original post. That could have been because of a water logged tank or multistage pump. Had intended for ebfixher to bleed and check tank first, observe, then change pump settings. Now that the possibility of a water logged tank has (hopefully) been removed, a return to original settings would confirm tank problem. A slow but consistent flow would indicate defective pump or low producing well. Just my logic.

If you are running sprinklers and a washing machine at the same time and holding 37#, that strikes me as not too bad.

Ebfisher,
By your comment to Hkstroud, does that mean that the pump was bad?

I wanted to point out that the tank will cause your pump to go bad. If it is allowed to become water-logged, it will sort-cycle and ruin your pump. I would recommend replacing the old-fashioned type of water tank that you have with a bladder tank. If you decide not to replace it, make sure that you completely drain the tank routinely.
Al