surging water pressure

I noticed surging water pressure ... when running water, the pump would turn on for only a couple seconds, repeating several times per minute. Alrighty, I first figured I needed a new pressure tank, due to an apparently busted diaphragm. (And I better do it fast, to avoid burning out the pump.)

BUT ... the tank sounds hollow at the top ... and no water comes out the air valve ... and I noticed the following odd behavior: if I turn off the pump breaker and let water out down to 15 PSI, then, upon turning on the breaker, the pressure increases slowly (as normal) from 15 to 30 PSI ... then the prs increases very fast (2 seconds) as the pressure increases from 30 to 60 PSI, where it turns off ... after it has reached this 60 PSI, then the gauge shows the pressure slides down quickly even if no water is running in the house. Upon reaching 60 PSI on the built-in gauge, a tire pressure gauge on the air valve indicates 23 PSI.

What's going on? Should I replace the prs tank?

Other background info: It's a submersible pump 150 feet deep; I installed the current WellXTrol tank 15 years go; there's considerable rust on the bottom third of the tank. I have hard water and have always had some bits of rust in the water.

Thanks for comments. Andy

Strange problem. Water pressure should not drop when pump is off and no water being used. The tank should not be rusty on the bottom third. The tank should not sound hollow as it is acting like it is waterlogged. I am guessing that the poppet came out of your check valve and is stuck in the inlet of the pressure tank.

Either way it sounds like you need a new check valve on the pump, and a new pressure tank.

Valveman, thanks. I'll replace the check valve and prs tank ... and let you know result. Andy