W124 1990 Fuel guage

[MotardMan]

I have just noticed that the reserve light is on, on my guage, but the needle is showing over 1/4 full. When I fuelled back up the tank took about 60 litres so was nearly empty. Any idea why the guage responds normally when full, but not as it approaches tank empty?

I guess I have the reserve light to fall back on, but I would prefer the needle to tell the truth too!

 

[twomercs]

I had a similar problem in my 2000 CLK, the needle was doing all manner of things. I had read of this problem in an earlier thread which suggested that the fuel sensors get coated in muck from cheap supermarket petrol and cease to function correctly. It was suggested that a couple of tankfulls of super unleaded form a non supermarket petrol station would clear the problem. Not having much hope with this suggestion I tried it and believe it or not after two tankfulls the fuel gauge is back to normal. It may just be a coincidence, but for the couple of quid extra per filling well worth a try. Let me know how you get on!!!

 

[Richard Moakes]

Or try some Redex or Fuel Injector Cleaner in the tank with the next fill-up.

Mine used to do that, a few fill-ups with additives sorted it for me.

Good Luck,

Richard

 

[pj]

I had exactly this problem with my 1992 190E. It was OK when full but the gauge would 'stick' at about 1/3 then the warning light would come on when nearly empty with the gauge still showing 1/3. It took me ages to find the fault. I eventually traced it to a bad contact on a potentiometer at the back of the gauge (looks like it is for calibrating the fuel gauge). I now have a W124 TE and the gauges look the same so it may be the same fault. Hope this helps.

 

[MotardMan]

twomercs, car has now had 3 tanks of Optimax, but sadly the gauge still lies!
Richard, will try some injector cleaner next.
pj, is a really nasty job to remove the instruments? I may have to have a go at that.

Thanks all for the posts, I'll keep this thread updated.

Best,

Jim

 

[Myros]

you'll need

the instrument cluster removal tools from MB, at about a tenner (great for recabling the soft top on a 107, another story), or make your own with some stout welding rod about 1.5mm dia. Bend the final centimetre back on it self to about 45 deg, insert the bent ends gently into the area by the widest point of the cluster, push down gently and keep a bit of twist on the rods, in an "inboard" sense. When the bent bits clear the back of the cluster, they will twist in, and you can gently pull the cluster out. You'll need to turn the wheel to get the cluster past it, or take it off. There is an excellent photo thread somewhere in the archive on this. Try a search on the key words cluster or cluster removal, or instrument panel.