I have a 1991 300D and the strangest thing started today, I was driving and the fuel guage dropped to halfway then back to full the to 3/4 then to full and then to half-way.
Is this a symptom of the sender in the tank going bad? If so, how hard is it to replace???

Sounds more like a loose connector on the gauge or the cluster. You have a W124 so you will have to pull the cluster to get at the backside of the gauges. Fuel tank is behind the rear seat. Sending unit is not too hard to get at. BTW, try giving the right side of the dash over the cluster a couple of pops with your hand before you pull it out, see if this makes any difference in the behavior of the gauge...

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Jeff L
1987 300e
1989 300e
1987 BMW 325

[This message has been edited by jeffsr (edited 06-09-2000).]

[This message has been edited by jeffsr (edited 06-09-2000).]

What are the procedures for pulling out the cluster, I understand that on the diesels this is a sensative procedure, if not done properly then trouble shutting off the car may be a problem, due to a mis-connected vacuum line.

I had the exact same problem with the pinball flipper fuel gauage in my 1990 300D. I tried playing with the connector to the fuel gauge sensor (on the fuel tank - accessible from the trunK0 - but this did no good.

My problem was that the fuel gauge indicator would act crazy only BELOW about 1/2 a tank of fuel. I finally decided to remove the sensor from the tank and test it. All the connections looked good. The sensor was covered (about half way) with a suity kindof black stuff.

It turned out that I had filled up with a 'dirty' batch of diesel somewhere - and some stuff had settled out from the diesel onto (the outside and inside - including the wiper) the sensor. I used some gasoline as a solvent - pour it into the sensor through some small holes ontop (hold the holes on the bottom closed with something - there were only two small ones on mine) and shake vigourously. Repeat twice. This did the trick for me.

mike

[This message has been edited by mike456 (edited 06-10-2000).]

This is a rsponse that someone sent me on another message board, what are your thoughts???

"I had the same problem with my 83 240D. It was a problem with the tail light. One of the bulbs in the tail light console was loose. I have also had it to happen when the plug to the tail light console gets knocked loose when throwing something in the trunk."

I had this problem on my 87 300d, and it was worse in cold
weather and when first starting out in the morning.

It WAS the connection to the instrument cluster. Further investigation revealed aftermarket cellular telephone wiring, sourced behind the instrument cluster. The connector wasn't on firmly and just needed to be pushed on more tightly.

Haven't had a problem since.

Justin



[This message has been edited by jrd (edited 06-10-2000).]

MIKe456,
Can you tell me exactly how you got to the sender in the tank? How do you take out the seats, where the sender is, any words of wisdom??

Any news???

Hi Ari,

I heard or read somewhere that it could be the connection to the lights in the back - but I have had the tail lights disconnected and I don't remember the fuel gauge acting weird in any way.

The sender in the tank is actually pretty easy to get to - with the right tool.

Remove the fabric/carpetting on the floor of the trunk, and then the one that is against the front of the trunk cavity (opposite the back seats). This will expose the fuel tank. You will then notice the fuel sensor plug and a large hex-bold-type head thingy.
Unplug the sensor connector (its a 3 or 4 pin plug which only fits one way). Might be worth checking it for any corrosion or bad solder connections.

The biggest part of this is undoing the hex screw. Its a very large size. We had to get a special socket from ackland-granger - as most other hardware shops did not stock sockets that big (btw. this same socket is the right size for the block heater - if you have one for cold environments and it burns out).

It does not take much force to undo it, once you take it out you will find 2 O-rings (On the hex screw) and the white top of the fuel sensor. The fuel sensor assembly pulls out easily (just up and out) - there are no other clips or screws or bolts holding it). The hex screw just rotates around the top of the sensor assembly, the sensor assembly is not directly connected to that hex screw.

Make sure nothing falls into the tank while you are working on the sensor. I couldn't figure out how to take the sensor appart, but for my fix I didn't need to - there were enough holes in the sensor to get the gas in and let it drain back out.

Put back in, careful to not over-tighten the hex screw (I couldn't find a torque setting - it really doesn't need much). Plug the connector back on and thats it!

hope this solves your problem.

mike

Mike,
Do you think it would be a problem if I used carb/fuel injector cleaner and sprayed it in the holes??

Mike,
I just looked in my trunk and I was wondering if I had to look under the actual spare tire?

Ding ding...

Hi Ari,

No, its not under the spare. You have to remove the carpetting that runs vertically against the FRONT of the trunk space - the fuel tank is sandwiched between the trunk and the back seats of the car.

mike

Call me crazy, but I have just a piece of carpeting, kind of like a giant floor mat for the trunk. When I lift that off and look in the trunk I have the spare tire on the right, a solid metal shelf and then the two little storage wells on the far left and far right.

I looked again and I do not see the sender??