main water line mystery

Heres whats happening, I had a regulator go bad (no water at all),replaced that and while setting concrete box back in I broke county water line.They come out and fixed it, went to house let lines outside run clear....ok have good pressure (65) for about 15 seconds then drops to 16 when small valve for bathroom sink open. Not using water it stayed at 65, I figured the county clogged my new regulator with their repair so I took it loose from line and made sure there were no obstructions ran good , plenty of water, great pressure put it back together ,now at house I have steady pressure of 16psi with no build up of pressure like before...here a few things to consider, from meter, line does cross under dirt road travels 900ft to house with an elevation increase of 35ft, line is 1' 1/4 pvc reduces to 3/4 about three foot from house not sure if its sched 40 or the 200... pressure and flow have never been great ,figured it was the climb up hill, but its never been like this. Any ideas???

pressure

Your regulator's strainer screen could be plugged, or the regulator itself could be jammed with some debris. Your description does not give any reason why you should have only 15 psi if the regulator is set for 65 psi.

The 35' elevation change cost you about 14 PSI. The 900 feet through 1 1/4" should not be a problem. The low static pressure just about has to be clogged regulator.

My thinking is theres another regulator in the line some where because the pressure should balance at 65psi on both sides of a blockage should there be one. The new regulator is definitely not blocked, shoots through there like a fire hose.I've tried to find the line further away from house so I could tie into and test the pressure but no luck yet in finding it. Is there any low cost way of finding pvc without locator equipment, and yes I tried diving rods or witching to no avail.....just not accurate enough