How to Replace a 1999 C230 Benz Fuel Sending Unit

1. Park your C230 in a safe, level location. Engage the parking brake or apply blocks to the wheels to prevent the vehicle from rolling. Open the trunk. Locate the trunk service area on the driver side wall of the trunk. Open the service area using a flathead screwdriver to open the release clips.
2. Locate the fuse box inside the service area. Open the fuse box panel using a flathead screwdriver. Locate the fuel relay inside the rear fuse box. Gently pull the fuel relay to disconnect the fuel relay.
3. Open the vehicle's hood. Disconnect the negative cable from the battery. Locate the fuel filler cap on the passenger side of the vehicle. Open the cap and insert a manual fuel siphon pump. Remove the fuel from the fuel tank using the siphon pump.
4. Raise the rear of the vehicle using a car jack. Apply jack stands to the rear axles to keep the vehicle elevated. Crawl underneath your vehicle from the rear. Locate the fuel tank on the passenger side of the vehicle. Support the fuel tank by applying a car jack underneath the tank.
5. Locate the first aid box inside the trunk area on the package tray. Open the first aid box and remove the first aid kit inside it. Inspect the package tray closely. Notice the package tray is secured by two screws. Loosen and remove these screws using a screwdriver.
6. Remove the package tray from the trunk area. Set the package tray aside in a safe location. Inspect the area where the package tray was located. You should now be looking at the top of the fuel tank.
7. Locate the cover for the fuel sending unit at the top of the fuel tank. Remove the cap of the fuel sending unit using a flathead screwdriver to pry the cap off. Set the cap aside. Underneath the cap is the fuel sending unit.
8. Remove the fuel sending unit using an adjustable wrench. Unscrew the unit and pull it up and out of the fuel tank. Discard the old fuel sending unit.
9. Replace the fuel sending unit by sliding a new unit into the fuel tank. Replace the cover for the fuel sending unit. Ensure the cover is screwed tightly to prevent a fuel vapor leak. Replace the package tray in to the trunk and secure it with the screws you previously removed. Return the first aid kit. Replace the fuel relay into the rear fuse box.
10. Remove the jack stand underneath the fuel tank and lower the vehicle to the ground. Reconnect the negative cable to the battery. Refill the fuel tank. Turn on the ignition. Allow the vehicle to idle for at least 10 minutes to pressurize the fuel system. During this time, inspect underneath the vehicle for a fuel leak.