I cleaned mine and nothing changed. Even though everyone said the sending unit was the issue. Granted its been proven it can be. So of course start there. But it not, remove the gauge cluster.

Easy to do, just search for directions. Once you get down to the fuel cluster and its removed you may see some resistors and a potentiometer (small dial). At least this is how it is in my 91 560SEL. After soldering EVERY part of the cluster I have gone back and just done the resistors and the pot again. Every time I solder it gets better.

But I think the pot and resistors are shot. If I look at the uncoated side of the board it looks baked. Others have noted that also. Also the gauge may be more accurate when just starting out then as things get warm the gauge may jump up to a higher level. So since I can no longer get it any better, next step is to replace them.

But one thing was clear, cleaning the sending unit did nothing and soldering the cluster did lots. So logic would say that sometimes its the cluster. After all, re-soldering stuff work very well for most VDO stuff it seems.

__________________
1991 560 SEL / 185k miles
1992 750il / 17k miles - project car