Shurflo 4008

How old is your pump? Mine did the same thing and it turned out the the leak was coming parting line where it comes apart. As JD said it is easy to take apart and clean. I did this 3 times and originally tried to get it to seal by just re torquing the bolts at the parting plane. What I learned is it does not take a big leak to draw air into the pump. I finally ended up putting a silicone adhesive along the parting plane to get it to seal and work again my pump was 18 years old at the time. The only tell tale sign was some corrosion under neath the pump which I could not see until the pump was removed. Check this if the other simple solutions don't fix your problem.

Some pumps have a screen on the intake side. I have replaced two that where cracked at the shop this winter season here in Quartzsite.

Some pumps have a screen on the intake side. I have replaced two that where cracked at the shop this winter season here in Quartzsite.

Old-Biscuit wrote:
DO you have a wet bay?
A water panel?

Fill valve?

Winterizing valve?

Could be fill valve still open allowing water to round robin to tank
Could be winterizing valve allowing air to get sucked in on suction side of pump
Could be cracked suction strainer...pump casing
Could be pump itself

Shurflo 4008 pump has an internal bypass valve.
Bypass starts opening at 40# and is fully open at 65#
But if stuck open pump can't build pressure or pump water to system

Not sure what a water panel is, but what I discovered after taking everything apart, and putting it back together, is it charged right up and shut off like normal. The clear plastic basket for the strainer on the inlet side was only lightly secured to the housing. Tightened finger tight on assembly, and that was the only loose point in the system. Works like normal. Thanks all that had ideas.