A ground from the "tank to the car chassis" is not going to ground the pump if there are rubber couplers. It might help the fuel gage sender but won't do anything for the pump. I do agree that a ground from tank sender to car chassis can help the reliability of the gage sender. Did you mean "from the pump to the car chassis? Pumps such as the Facet have two wires, either one of which can be grounded, depending upon the car polarity.
D