JB7

Another thought. Davco recommends draining the water from the bottom of the unit once a week. If this is not done the base can get corroded internally. All it would take is a little bit of that corrosion to break off and get between the check valve ball and seat. The result being fuel leaking out of the unit back to the line or tank.

1 - The Davco test in the manual available online (pg 19 for Model 382) states that slight seepage is normal when testing the check valve. A little seepage can add up over several days. 2 - Davco states to use a thread sealant when installing the check valve and torque to 44-60 ft-lb. 3 - All it would take would be a spec of dirt or sand to get between ball and seat to cause drainage. Maybe crud coming out of the tank. Or check for any fine particles in the base and blow out with brake clean and compressed air. Doubt it but there may be corrosion in the base or crack. If no external leak the only place it can drain is back through the check valve.