My Shureflow 5.7 has been running great for 7 years. Plenty of water(no difference when another faucet is turned on) and so quiet we never hear it come on. My understanding that many problems are related to low voltage and leaky lines.
My 5.7 was cycling since new. Recently I tried new valve body and it was worse than the original. So I ordered a different pump as I stated in my previous posts. Before throwing the old pump away, I decided to try to fix it.
The valve body has 10 valves. The possibility that one of these valves will develop leak is fairly high. So I decided to give all of these valves good cleaning. I used isopropyl alcohol soaked q-tips and paper towel. Alcohol swabs would work also. Spent more than an hour wiping and wiping until no black residue showed on q-tips. After reassembling the pump the pump works fine. So I did not install new pump for now and keep it as spare.
The 5.7 Shurflo is a good pump when it works. I think better material like Viton should be used to make valves instead of the EPDM. It seems that oxidized EPDM residue on valves and valve seats causes poor seal and causes pump cycling. The pump does not have a separate check valve.
* This post was
edited 03/18/12 10:16pm by liborko *