Difference in fuel pumps?

DARTLARRY said
When I bench tested it, it pumps fuel, when installed on the car and turning the motor over and fuel line disengaged and placed into a bucket it does not pump fuel.
Witw it still installed on the car, and using an electric pump and gas can to run the engine, it still does not pump fuel.

10 inches vacuum, 5 to 7 psi. Hook up a gauge. Maybe it is pumping........... pumping air that is.

Jack the back of the car up; Open the gas cap. The gas should find it's way to the front by gravity, and run out of the hard line by the pump.