Brand New Electric Fuel Pump Wiring Harness Pigtail This wiring harness pigtail connector is used when you are installing a new fuel pump that has a 4-pin square connector instead of the flat connector. The flat connector is used on early models and most aftermarket fuel pumps can come with either the flat or the square connector. Fits all 4-pin square fuel pump connectors found on 1996-2007 Chevy/GMC/Buick/Pontiac/Oldsmobile/Isuzu models