How to Change a Fuel Filter in a GMC S15

by Gregory Crews
pumping gas image by Mat Hayward from

The GMC S-15 is a light-duty pickup truck made for work and dependable transportation. Changing the fuel filter will help to keep the truck running efficiently. The filter needs to be changed every 30,000 miles, as sediments can quickly clog the filter and eventually seep into the engine causing bad performance and bad fuel economy.

Step 1

Open the hood to access the engine compartment. Locate the fuse relay box behind the battery. Open the panel and pull the relay for the fuel pump by hand.

Step 2

Start the truck to let it idle. The truck will stall once the fuel system is depressurized. Insert the relay back into the fuse panel.

Step 3

Crawl under the truck by the driver-side door. The fuel filter is located under the driver-side door.

Step 4

Loosen the outlet line with a line wrench. There will be two nuts on each side. The one attached to the filter is stationary and needs to be held with a line wrench. Use the second line wrench to loosen the fuel line. Pull it away from the filter. Remove the inlet line the same way.

Step 5

Loosen the mounting bracket with a socket wrench. Slide the filter away from the bracket.

Step 6

Position the new filter to the mounting bracket and install to the truck frame with a socket wrench. The arrow on the filter needs to be pointed toward the front of the truck. The arrow designates the direction of fuel flow.

Step 7

Install the inlet line to the filter by hand. Tighten the line with a line wrench. Hold the stationary nut on the filter with a line wrench. Repeat to install the outlet line.

Step 8

Turn the ignition key to the "Start" position. Allow the fuel pump to push fuel through the fuel line. This will also purge the air that is in the fuel lines. Turn the key to start the truck. Repeat this step as the truck may not start right away.

Observe the fuel filter while the truck is running. Ensure there are no leaks coming from the filter or the fuel lines.


  • The truck may not start right away as there is air in the lines. Turning the key to the "Start" position will prime the pump and push the air out of the lines and replace it with fuel. Once the fuel reaches the engine the truck will start.


  • Use caution when working around gasoline as it is toxic.

Items you will need

  • Line wrench set
  • Socket wrench
  • Socket set
  • New fuel filter

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