Weak pump pressure

[CRchris]

I installed new back-up water system, cistern - gravity feed 12" head, 3/4 hp pump. everything works, but pump cycles up to 46 lbs, keeps running for 30 secs, then shuts off. Is it common for a pump to be that weak, brand new? I have adjusted the switch to a higher setting - 35lbs, and the upper limit screw higher, but same results. Appears that the pump can only do 46 lbs. Considering the problems that happen in costa rica, maybe the pump sat too long in the heat, or something else that might affect the seals.

 

[Valveman]

Sounds like you have one of those little gizmos that shuts the pump off at no flow, and turns it back on at a reduced pressure? Lots of names for them like masscontrol, presscontrol, burcam, etc. They sit on top of the pump and will shut the pump off about 30 seconds after flow stops. And yes they are usually low pressure type pumps, as these gizmos have no control over the pressure. If the pump could build 100 PSI, there would be 100 PSI in the house. So they only use them with pumps that can only build 46 PSI or so.

Send a pic and/or a pump model and we can look it up to see how much pressure you can get.