The fuel filter location varies with engine size on the Kia Optima. The 1.5-, 1.6- and 2.4-litre engines have the fuel filter located under the car in the front left corner of the fuel tank. The 1.8-litre engine has the fuel filter located on the driver’s side firewall. All the filters have the same replacement procedure. There are actually two filters on the Kia Optima. A filter called a strainer is attached to the intake side of the fuel pump inside the fuel tank.
Lift the bonnet and remove the cap on the fuse and relay box located on the driver’s side fenderwell. Look at the bottom of the cap for the location of the fuel pump relay within the box. Pull the fuel pump relay out and lay it sideways in the box.
Start the engine. It is not likely to start and even if it does it will only run for a second since the fuel pump relay has been removed, which disabled the fuel pump. This procedure will drop the fuel pressure in the fuel line. Raise the rear of the vehicle with the floor jack and support it by the frame with the jack stands. This is for engines 1.5, 1.6 and 2.4.
Remove the fuel lines on both ends of the fuel filter. Use the scribe--a long pointy needle--to lift the white retainer straight up located in the centre of the connector. This releases the fuel line from the fuel pump. Do the same to the other side of the fuel pump.
Remove the bolt in the centre of the fuel pump retainer bracket using a 10mm socket. Pull the fuel pump out of the bracket.
Insert the new fuel pump into the retainer bracket. Make sure that the inlet side faces the fuel line to the fuel tank and the outlet toward the fuel line to the engine. Install the fuel pump and bracket and tighten the bolt.
Place a white retainer clip that came with the filter into the holes in each of the connectors. Just push it in enough to snap the bottom ends of the clip in place. The clip should now be standing straight up with just the bottom tips in the connectors. Push each of the fuel lines into the filter one at a time. Holding the fuel line tightly into the filter, push the white retainer clip down to lock the fuel filter and fuel line together. Lower the car and replace the fuel pump relay. Start the car and check for leaks.