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Autopapyrus · Kia Optima 2.4 GDI G4KJ (2019)
https://autopapyrus.com/guides/kia/optima/fuel-tank-replacement/
Compiled automatically from service literature and owner experience. Specs are for the typical configuration — check them against your exact car before you start.

Kia Optima 2.4 GDI G4KJ (2019): Fuel Tank Replacement

On the Optima JF, the fuel tank is located under the rear floor, held by two steel straps and supported by the body. The work is done from underneath, without removing the rear seat. The main thing is to make the fuel system fully safe: drain the fuel, relieve the pressure, and work away from sparks. The fuel pump module (with the level sensor) is usually transferred from the old tank to the new one.

Difficulty: Hard Time: 3-5 hours Steps: 13 Tools: Vehicle lift or pit (jack stands are not recommended), transmission jack or tank support stand, 10/12/14/17 mm socket set and ratchet, torque wrench, fuel line retainer release tool, manual siphon pump, fuel containers, fire extinguisher, gloves, safety glasses.

Part

  • 🔩 Fuel tank assembly for 2.4 GDI: Kia 31150D5500 (per catalog data; confirm by VIN to be sure). The left and right tank straps are purchased separately. Additionally: fuel pump module seal ring/gasket and new single-use clamps/retainers if they are damaged during removal
There's a full repair manual for this car Every system, wiring diagrams and torque specs — not just this job. Haynes and 4 more. See manuals →

Step by step

13 steps
  1. Preparation. Work in a well-ventilated area, away from open flames and sparks. Disconnect the negative battery terminal. Open the fuel filler door and remove the fuel filler cap to relieve pressure in the tank.
  2. Relieving system pressure. Remove the fuel pump fuse and relay (locate them using the fuse box cover diagram in the engine compartment), start the engine and let it stall. Crank the engine with the starter for 2-3 seconds to finish relieving the pressure. Then disconnect the battery again.
  3. Draining the fuel. Ideally, run the car down to a minimal fuel level (the tank on this model holds about 70 L (18.5 gal)). There is no drain plug on the tank, so pump the fuel out with a manual pump through the filler neck or through the pump module access opening into an approved container. Never siphon fuel by mouth.
  4. Raise the vehicle on a lift and, if necessary, remove the rear right/left wheel for access to the filler neck. Remove the lower underbody splash shields if they obstruct access.
  5. Exhaust system and heat shields. If the heat shields or the exhaust pipe block access to the tank straps, remove the shields above the tank (10 mm bolts). If necessary, lower the exhaust system or loosen the hanger mounts, but only as much as needed to remove the tank.
  6. Access to the pump module. For the connectors and fuel lines on this model, it is easier to lower the tank a few centimeters and work from the top of the tank: disconnect the pump module electrical connector, the fuel supply line (quick-release retainer; use the release tool and do not pull it off by force), and the EVAP (vapor recovery) hose.
  7. Filler neck. Disconnect the filler neck hose from the tank (clamp) and the vent/vapor recirculation hose. Place a container underneath beforehand, as residual fuel will run out.
  8. Tank support. Position a transmission jack or support stand with a wide wooden pad under the center of the tank. A tank with residual fuel is heavy; do not set it on sharp edges.
  9. Fasteners. Remove the bolts/nuts of the two tank straps (usually 14 or 17 mm) and swing the straps downward while holding the tank. Check that nothing (hoses, wiring harnesses, brake lines, brackets) is still holding the tank.
  10. Slowly lower the tank and remove it from under the body. If it needs to be turned over or laid down, do so only on a flat surface, away from sparks.
  11. Transferring the pump module. Clean the area around the flange of dirt. Remove the lock ring/flange screws of the module and carefully lift out the module (do not bend the level sensor float). Replace the seal ring and install the module in the new tank in exactly the same position. If you are replacing only the tank, check the condition of the strainer (filter sock) on the pump.
  12. Assembly. Install the new tank in reverse order: raise it with the jack, connect the lines and connector, the EVAP hose and the filler neck before final tightening of the straps (otherwise they cannot be connected). Tighten the tank straps securely (check the exact torque in the manufacturer's service manual; as a guideline, roughly 40-60 N·m (30-44 lb-ft) for the strap mounting bolts; do not overtighten, to avoid deforming the straps).
  13. Checking. Reinstall the shields and heat shields, reconnect the battery, and add 5-10 L (1.3-2.6 gal) of fuel. Turn the ignition on for 2-3 seconds several times (the fuel system will build pressure) and inspect all connections for leaks. Start the engine, check for any gasoline smell, and make sure there are no Check Engine codes and that the fuel level sensor works correctly.

Common mistakes and warnings

  • This job involves a high fire risk: gasoline vapors are explosive, so do not smoke, do not use incandescent work lights or open flames, and keep a fire extinguisher nearby. On a GDI engine, the high-pressure fuel line remains pressurized even after the engine is stopped, so always relieve the pressure as described above before disconnecting any lines. The low-pressure side (feed pump) and the high-pressure side (after the high-pressure pump) are separate sections; the tank works on the low-pressure side. If you have no experience working on fuel systems, leave the job to a repair shop. Check the exact tightening torques for the straps and the pump module fasteners for this model in the manufacturer's service manual.