2009 Chevrolet Trailblazer Fuel Sending Unit

First, you need to remove the fuel tank, unlock the fuel sender lock ring, and remove the fuel sender assembly and the seal. Then, please clean the fuel sender sealing surface. Finally, you should place the lock ring on a flat surface and measure the clearance between to lock ring and the flat surface using a feeler gage at 7 points. If the warpage is greater than 0.41 mm (0.016 in), the lock ring must be replaced.

First, you need to install the new seal on the fuel tank and install the fuel sender assembly into the fuel tank. Then, please install the fuel sender lock ring and turn the fuel sender lock ring in a clockwise direction. Finally, you should install the fuel tank.