W210 - Inaccurate Fuel Level
 

97 E420, 80K miles... fuel gauge always reads full following renewal of the level sender. (The original sender was damaged by fuel with a high sulfur level.) Prior to sender replacement the gauge would read full at engine startup and then fall to a lower level during the drive. Now the gauge constantly indicates full; the low level warning light is functional during engine startup.

With the sender's leads disconnected the fuel gauge reads 1/4. Connected the leads to a second, new sender and manually moved the float... still the gauge reads full, regardless of the float arm's position.

Is this an instrument cluster problem??

Anyone?

In my opinion yes. Or possibly a wiring problem.
A more accurate test would be to use a resistance substitution box to replace the sensor, and find out what specs to use to obtain a full reading, 3/4 reading, 1/2 tank reading, 1/4 tank and empty. These specs should be in a diagnostic manual and other sources I'm sure.
The Star Diagnosis computer may also be an aid in diagnosing this problem.

Gilly

Well, its definitely the instrument cluster.

Removed the existing cluster and installed a good cluster from another vehicle... gauge in transfered cluster worked properly. Installed the defective cluster in the donor vehicle.. gauge indicated full.

M-B's instrument cluster for this vehicle is > $800, reman'ed and > $1200, new.

Anyone repair these in the aftermarket?

Possibly. There is a place I believe someone mentioned in Florida that rebuilds R129/W140 clusters, let me try a quick search for that thread......
Gilly

Try this thread, 4th post:

http://www.peachparts.com/shopforum/showthread.php?threadid=88030&highlight=florida+instrument+cluster

Gilly

Or this thread, 9th post, lists another Florida company:

http://www.peachparts.com/shopforum/showthread.php?threadid=80155&highlight=florida+instrument+cluster