IF he has a water panel with switches/valves then have him check the 'Fill Valve' ----needs to be fully closed or pump can not build enough pressure to shut down.
Other thing.....all air needs to be purged from system ---hot/cold system not forgetting outside faucet
If pump has an internal bypass then adjustment to discharge pressure settings and bypass open/close settings may be wrong ----discharge pressure higher then bypass full open setting---never reaches discharge set point
Shurflo 4008/4048 pumps
Is it time for your medication or mine?
2007 DODGE 3500 QC SRW 5.9L CTD In-Bed 'quiet gen'
2007 HitchHiker II 32.5 UKTG 2000W Xantex Inverter
US NAVY------USS Decatur DDG31