Buick 6472020 Fuel Pump Assembly

The process for replacing a mechanical pump on carbureted models involves disconnecting the battery cable, detaching the fuel inlet hose, outlet line, and vapor return hose, removing the mounting bolts, and retrieving the pushrod. After cleaning the block mounting surface and applying grease to the pushrod, the new gasket and pump are installed and the hoses and lines are reattached. For electric pumps on fuel-injected models, the fuel system pressure is relieved and the fuel tank is removed. The fuel pump/sending unit assembly is unlocked by turning the inner ring counterclockwise, and then lifted from the tank. The rubber gasket and strainer are inspected and replaced if necessary. If needed, the fuel pump can be separated from the sending unit. The assembly is then inserted back into the fuel tank and the inner lock ring is turned clockwise to engage the locking cams. Finally, the fuel tank is installed.

First, remove the dust plugs from the inlet and outlet fittings of the pump.

Testing involves checking the suction side from the tank to the pump and the pressure side from the pump to the carburetor.

For fuel-injected models, start by verifying that the fuel pump is running by listening for a whirring noise when the ignition switch is turned on. If the pump does not come on, check the fuel pump fuse and relay. If they are both functioning properly, check for an open circuit between the relay and the fuel pump. If the circuit is fine, disconnect the electrical connector at the fuel pump and connect battery voltage to the gray wire terminal of the pump to see if the pump runs.

When installing the new pump, ensure to use a new gasket and apply gasket sealant on the screw threads.

If no spurts are present, replacement of the pump is necessary.

The rubber gasket and strainer should be inspected and replaced if necessary.