W126 evil fuel gauge, sorta fixed, need help...
 

I've been working on this one for a while. 99% sure its not sending unit as other have mentioned. Already cleaned it, but there always is that 1% chance.

The reason I do not think it is the sending unit is that after cleaning there was no change in gauge behavior. However, after soldering some components on the cluster board there was a dramatic (and more accurate) change.

So fast forward to this weekend. I replaced the three resistors on the board. The old ones read between 68 and 75 ohm. When heated up with a hair dryer, they went up and down with resistance.

But with new ones, the gauge does not still read correctly. However, its a little more accurate. Once operating for a while, it starts to fluctuate. I think the fault id the potentiometer. I ordered one, but its the wrong size.

Can anyone help with identifying this exact part?

! would connect a resistor across the sender unit pins to see if the needle still fluctuates while driving .

In my 89 300SE adding a certain fuel injector cleaner effected the sender unit operation,. Cleaning it would restore steady operation. . Now i use Redex cleaner occasionally with no detrimental effect .

regards

Never thought of that, good way to rule it out 100%. Wonder if I can locate the proper pin-outs at the cluster connector. Would make is a little easier.