car stalling

i cranked the motor and got the fuel to pump into a bottle. but, when i let off the ignition, the rubber hose sucked the fuel back down the line towards the pump. pretty quickly too, i might add.

i rechecked the connections at the fuel pump. additionally, i checked along the hard line aft of the pump as well as the flex line to the tank. no leaks or drips anywhere.

when the car is being cranked, the pump seems to be pretty strong. i get a good amount of fuel coming thru the line.

my mechanic friend explained there's a check valve inside the fuel pump that ensures fuel flow in only a single direction.

if the check valve is working properly... my reasoning is that even if there's a problem aft of the pump, the one-way valve should prevent fuel from going back down the line, and fuel should remain in the line even if the car is not running, and the filter should subsequently remain full.

do you think the check valve in the fuel pump is the culprit? i'm going to have napa swap the pump tomorrow. but i want to hear your ideas as well.