Shurflo 4008 won't stop running.

My guess is there is a leak, but not on the intake side. If the output side of the pump comes up to pressure (no leak or something demanding water) then it will come up to pressure and the pressure switch will shut it off.

BendOrLarry wrote:
My guess is there is a leak, but not on the intake side. If the output side of the pump comes up to pressure (no leak or something demanding water) then it will come up to pressure and the pressure switch will shut it off.

Should I have used Teflon tape on the threads on the pump in and out? ? Would that allow air to get by? I will tighten all the hot water line valves I just did, I think it's on the pump it self you can hear air like a old compressor

buckarooman wrote:
I have a brand new shurflo 4008 pump that won't quit running. The tank is full the winterize valves are all open, and I have the silence kit with soft lines because the water lines wouldn't reach the new pump. It sounds like there's a air leak on the inlet side if the pump but every think is tight, is there anything on the front of the pump that would suck air thay maybe loose? If you jack with it for a bit it will finally make pressure and stop.

On the bottom of the pump there is an adjusting screw,(Phillips)which controls the amount of pressure required to shut off the pump. It is very sensitive and only requires slight adjusting. Over-doing can destroy the diaphragm.

harold1946 wrote:

buckarooman wrote:
I have a brand new shurflo 4008 pump that won't quit running. The tank is full the winterize valves are all open, and I have the silence kit with soft lines because the water lines wouldn't reach the new pump. It sounds like there's a air leak on the inlet side if the pump but every think is tight, is there anything on the front of the pump that would suck air thay maybe loose? If you jack with it for a bit it will finally make pressure and stop.

On the bottom of the pump there is an adjusting screw,(Phillips)which controls the amount of pressure required to shut off the pump. It is very sensitive and only requires slight adjusting. Over-doing can destroy the diaphragm.

I've never messed with it I wonder if it's possible it's loose from the factory and letting air by?

The pump may not prime if some downstream water taps are not opened to allow water to flow through the pump.

Harvard wrote:
The pump may not prime if some downstream water taps are not opened to allow water to flow through the pump.

That's a good point shoukd just make a point of opening the bathroom sink

buckarooman wrote:

Harvard wrote:
The pump may not prime if some downstream water taps are not opened to allow water to flow through the pump.

That's a good point shoukd just make a point of opening the bathroom sink

Air IN leak can ONLY happen on suction side of pump........

Discharge side of pump will cause water to leak out IF there is a loose/cracked line/fitting

BUT pump can NOT prime and move air from system if a faucet is not initially open giving the air in system some place to be expelled


As for 'adjustments'

Be careful because there are 2 adjustment screws
1 for discharge pressure
1 for bypass function

Get one or other wrong and pump will NEVER shut off.
Adjustments should be done with pressure gauges and understanding of how bypass functions/at what pressures it opens/closes and how it interacts with pump discharge pressure.

I got it! This took forever to track down, there was two things that was wrong. The tight space for the pump I wasn't able to see that the strainer was cross threaded and sucking air, and the regulator was off just a bit. I bumped the screw in a half a turn and it instantly shut off, and 9n a side note after ditching the hard lines for flex this things quiet. Thanks for all your help guys