How to Diagnose a Bad Fuel Filter
- 1). Pay attention to your vehicle. Are you having trouble when starting your vehicle? Does the engine stop abruptly, like your car is running out of gasoline? Are there issues with acceleration, engine performance, or misfiring? Is there a strange exhaust fume odor? All of these are signs that the fuel filter may be clogged or partially blocked, and needs replacing.
- 2). Put on eye protection before determining whether or not your fuel filter needs to be replaced.
- 3). Allow the engine on the vehicle to cool down before moving on to any of the next steps, especially if the vehicle has recently been driven for longer than five minutes.
- 4). Locate the fuel pump fuse in the fuse box, or the relay that controls the fuel pump. Start the car. While the car is running, remove the fuse or relay. The engine will die after you've pulled the fuse or relay out of the vehicle. This removes the pressure in the fuel lines.
- 5). Disconnect the fuel lines from the fuel filter using an open-end wrench. A bolt should come out. Move the fuel line away from the bolt and place the bolt to the side. Repeat this step for the other side of the fuel filter.
- 6). Use a flat-head screwdriver in order to remove the clamp that's holding the fuel filter in. Not all vehicles have clamps, so yours may not.
- 7). Remove the fuel filter from the vehicle by gently and carefully pulling it out.
- 8). Use a small rubber hose or tube to test the filter by attaching the tube to the fuel filter and blowing into the tube. If there is little resistance as you blow, the filter is in good shape. However, if there is more resistance, the filter needs to be replaced.