DIY - Fuel sender: LEFT side [Archive] - Bimmerfest - BMW Forums

: DIY - Fuel sender: LEFT side

03-02-2009, 07:38 PM
- Fuel gauge reads fine until nearly half-empty and then suddenly shows empty.
- You can determine you have this problem by going into the diagnostic menus and looking at the TANK data. You will be able to read the LEFT and RIGHT tank values. The computer somehow adds these together to get a total reading. It seems, if you have a problem, your LEFT tank will continuously read ZERO (see picture).

I ONLY DISCUSS the LEFT fuel sender in this. HOWEVER, the RIGHT fuel sender would be very similar to replace.

- I believe this is caused by the carbon resistor material that the contact of the fuel sender arm rubs against which wears off over time.

STEPS (non comfort/cooled seats)
1. Release rear seat bottom - pull up briskly at front left and front right of seat (stick hand underneath between carpet and seat bottom)
2. Disconnect heated seat cable on left bottom of seat. It is a plug with a clip. Just move the clip up and the connector should come loose.
3. Pull seat out (helps if you have a helper).
4. You will see two circular covers on the left and right of the underneath of the seat. Remove the four nuts holding the left cover down.

AT THIS POINT I RECOMMEND YOU GET SOME TRASHBAGS AND LAY THEM DOWN AROUND THE FUEL SENDER COVER AREA IN CASE YOU SPILL SOME GAS. You don't see it in the pictures, but I did this as well to help prevent any spills.

5. Carefully lift cover and unplug the sensor plug from the fuel sender. Unplug the small fuel line. A small amount of fuel WILL COME OUT.
6. You will see a retaining ring that holds the sender in place. On top of it are protruding points. There is a special tool you can use to get leverage on the top of these points and attach a ratchet. However, I used a flat blade screwdriver and a small mallet. You can position the end of your screwdriver against the protruding points and hammer the back of the screwdriver such that you turn the ring counter-clockwise. Once completed, you will be able to remove the ring. You can take a similar approach to tightening it.
7. Carefully lift the fuel sender out. WATCH and grab onto the O-RING directly underneath the ridge of the fuel sender, you don't want to lose this in the tank! There is a suction jet attached to the fuel sender. You WILL NOT be able to pull it out completely until you disconnect the suction jet connection. This is a plastic connector with a tab that you can press to release it and pull it off. Carefully disconnect it (it WILL NOT drop to bottom of tank, so don't worry :-)).
8. Insert a new Fuel Sender with new O-ring. ENSURE you completely push the suction jet hose back onto the new fuel sender. I pushed it as far as it would go (you don't want this coming loose later - heh).
9. Screw retaining ring back over the fuel sender. Use mallet+screw driver method to torque it down (or buy special tool if you are sensitive ;)).
10. Follow remaining steps in reverse and you are done!