GMC 12682079 Fuel Pump Assembly

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Disconnect the cable from the negative battery terminal. Relieve the system fuel pressure. Remove the fuel tank. Disconnect the fuel supply line, vent line and electrical connectors from the fuel pump/fuel level sending unit module. Use a shop rag to soak up any spilled fuel. Using a pair of large water pump pliers, unscrew the fuel pump/fuel level sending unit module lock ring by turning it counterclockwise. If the lock ring is tight, use a hammer and a brass punch to loosen it. Be careful not to distort the lock ring, or it will have to be replaced. Note the orientation of the fuel pump in relation to the fuel tank to ensure that the fuel pump is correctly realigned when you install it again. Remove the fuel pump/fuel level sensor module, taking care not to damage the fuel level sensor float arm and float. Before installing the pump, inspect the pump-to-tank seal. It's recommended to replace the seal whenever the module has been removed. Installation is the reverse of removal. Align the fuel pump/fuel level sending unit module with its hole in the tank and carefully insert it into the tank, then align the marks noted earlier. Make sure that you don't damage the fuel inlet strainer, the float arm or the float during installation. If the float arm is bent, the fuel level that is indicated on the fuel level gauge on the instrument cluster will be incorrect. Whenever the battery has been disconnected, the Powertrain Control Module (PCM) must relearn its former driveability and performance characteristics.

Start by removing the oil filler cap and engine cover fasteners. Lift the engine cover and valve cover insulator off of the valve cover and reinstall the oil filler cap. Relieve the fuel system pressure and disconnect the cable from the negative battery remote terminal. Disconnect the fuel pressure sensor electrical connector and unscrew and remove the sensor from the fuel rail. Clean the threads in the fuel rail and apply a drop of oil on the new sensor threads before installing it. Remove the sensor again, apply another drop of clean engine oil on the threads, and reinstall it. Connect the sensor electrical connector and reverse the removal process.

To perform a fuel pressure check, locate the Schrader valve test port on the fuel rail (on 2016 and later models, high-side fuel pressure can only be checked with a scan tool).

Mark the orientation of the fuel pump in relation to the fuel tank for proper realignment during installation.

The initial steps to remove the fuel pump are relieving the fuel system pressure and disconnecting the cable from the negative battery terminal.