Things You'll Need
Pliers
Replacement fuel filter
Fuel filters ensure that the gasoline being delivered to your engine is clean and free of harmful debris. They keep your engine supplied with clean gasoline to help it run smoother and last longer. Fuel filters do get clogged, however, and will need to be replace usually every 24 months.
Step 1
Open the fuel door and remove the gas tank cap located on the driver's side of the vehicle. Pop the hood and locate the fuse box over the driver's side wheel. Use the diagram underneath the fuse box cover to find the fuel pump relay and disconnect it.
Step 2
Get in the vehicle and crank the engine. Allow the engine to sputter and stall out until it shuts off. This shouldn't take more than a few seconds, and must be done to relieve pressure from the fuel system.
Step 3
Use the pliers to disconnect the negative battery cable. Disconnecting the battery will keep the fuel system from re-pressurizing.
Step 4
Engage your vehicle's parking brake for safety. Locate the fuel filter underneath the middle section of the vehicle on the driver's side. If you have trouble locating the fuel filter, look directly in front of the gas tank, next to the frame rail.
Step 5
Use the pliers to remove the locking nuts around the fuel filter. Be careful when removing it. Although you have released the fuel system pressure, some gasoline may still drip down.
Step 6
Install the new fuel filter with the arrow pointing towards the rear of the vehicle. Re-attach the locking nuts with the pliers. Plug the fuel relay back into the fuse box and re-attach the negative battery cable. Put your gas cap back on.
Step 7
Start the engine and inspect the new fuel filter for leakage. If you have properly tightened the nuts, leaks should not be present.
Tip
Make sure you purchase a fuel filter compatible to your Trailblazer. Chevrolet recommends using genuine GM replacement parts. This procedure is also applicable to the GMC Envoy, a mechanical twin of the Chevrolet Trailblazer.
Warning
Do not attempt to change the fuel filter before relieving pressure from the fuel system. Fuel is under high pressure and can be very dangerous.