Shallow irrigation well - from great to nada.

Hello all.
I have a shallow-well yard irrigation system which has performed perfectly every Summer for years; common 1 and 1/4" driven PVC paired with a STA-Rite 3/4 hp pump. I've used it for 12 years, the well itself could date back to the 1960's. The well is 25ft deep with the static waterline at 13ft (checked that this morning.)

View here::http://BrianMcCulloughShow.biz/WellHead&Pump.jpg (I'm anticipating putting in underground sprinklers soon, so, yes, that's all new PVC you see - new air tank, check valve, the pump was given new seals (everything else in it, impeller, injector, etc was OK. Tested in a barrel.) Put system back together, and all working fine for several weeks after the "refurb."

Yeah, things were going too...well. At startup today my normal 9gpm flow is down to a surging dribble, and not enough oomph to trip the on-at-30/off-at-50 pressure switch.

The pump holds its prime. The pressure switch works.
I tested for leaks on all the joints - inlet & outlet side with soap.
I don't think there could be a foot valve since I'm pretty sure it's just a pounded in wellpoint.
We've had nowhere near our normal amount of rain this Spring in South Carolina, so I cut below the check valve and dropped a line in to make sure "hey, dummy, y'all ain't gettin' water 'cause there ain't none"...and water was there at 13ft.
I ran a hose with city water all the way down the 1 & 1/4" casing to see what would flush out, got clean water back up with a very slight trace of sand. Let the garden hose (with approx 25# city water pressure) run into the well for 10 min, and it took it easily. Put everything back together, no improvement.

The above pretty much exhausts my repertoire of well smarts. What's my next move?
Thanks in advance for all who are kind enough to comment.

 

Try clearing the orifice with a wire.
See https://terrylove.com/forums/index.php?threads/pressure-drops-quick.67304/page-2#post-500629

The wire diameter is not critical. A wire cut from a coat hanger is often suggested. 12 gauge electrical wire is probably suitable.

Your PVC should be protected from long-term sun. This could be with paint, tape, or a cover.

 

Reach4, Valveman...Ran coat hanger through venturi nozzle, no blockage. Ran pump briefly with city-water input through one of the discharge hose bibs, and the venturi access plug out to wash out any crud just in case. (That did prove the pressure switch working.) Closed up, reprimed; same result - poor water discharge, lots of air.

So, that leaves the only remaining reason a suction-side air leak?, and since I don't see anything above ground, it's got to be below? Am I correct in assuming there isn't any cure for that other than boring a nearby new hole?

P.S. Pump & well have a cover, just is off for access & photo.

 

Pump ran fine with a fishpond water as alternate intake source instead of the well. Was also tested after being rebuilt.

I did not find any above ground suction leaks with soap, so wound Saran wrap from wellhead to pump, didn't make a difference.

 

Pump was running w-vacuum with intake line wrapped in Saran, brings up some water, just not much. I thought perhaps if discharge increased when wrapped that would point to the air leak being along the inlet piping above ground. I'll unwrap and try again with shaving cream tomorrow, it's started to thunderstorm now.

 

OK, fast forward one day. Checked venturi again, is clear. No airholes with the shaving cream, same behavior with running pump...holds prime overnight, with outlet bib closed builds pressure and shuts off >> open bib >> good water 'till pressure falls enough to have pump kick in, then flow slowly falls off to no better than a steady dribble.

I'll dig up around wellhead tomorrow when it's cooler and see how far down I can get in search of a possible air-leaking joint near the top. Then, the only options left are pull the 25' of PVC and inspect?, or sink a new wellpoint & PVC next to the old?

 

If you can put a vacuum gauge on the suction line without introducing a suction leak, you could get info.

If vacuum is high, water is too far down after you pump a bit, or the inlet screen is plugged.

If vacuum is low, pump is bad, or there is an air leak, or your well runs out of water.

If your well runs out of water and admits air at the input screen, I would expect air in your water. You did not report air in your water.

 

(Hello again Reach4)
Re: air in water...only a bit/a few "coughs" when first starting, but not ongoing.
I won't be able to get away to buy a vacuum gauge until late next week, could you comment on this small insight?...just for shiggles and gits I unscrewed the plug on the pump (above where the venturi is internally) and held my thumb over the hole. Felt the suction, but seemed pretty mild, I was expecting much more. Would you take this "analog organic vacuum test" as pointing towards air leak rather than clogged-up wellpoint intake? Water level @ 13ft a few days ago, so I know I'm not out.

 

I don't have an expectation/guess of what the vacuum there should be.