recently installed a new pump and pressure tank for a neighbor after a leak in a pvc coupler burned out a 30 year old Sta-rite 1hp shallow well pump suction is 1 1/4" with 1" discharge new pump is a Zoeller 1hp, wired 110v using a square D 40/60 switch. pressure tank is a water worker 20 gal charged to 38psi issue i am having is when i turn the power on the well will instantly charge up to 60 psi as it should but as the system drains the flow rate will quickly drop to a trickle as the pressure tank drains, when the pump turns on the pressure gauge will drop to zero and remain there then when the pump shuts off it will jump to ~ 38 psi and generate no water pressure to the house feed line. neighbor did not want to use the included control body due to the positioning of the original lines and not wanting to cut out and redo the entire pvc system so the pressure gauge and pressure switch or mounted to the 1/4 fip holes in the pump body anybody have any ideas about whats going on here?

I need help trying to get my water going!! Please!..it's really hard to explain what happened with the control box and pressure switch and well pump..************************