96 C220 fuel sending unit/gas guage

[TCCBass]

Greetings! I'm posting this for a friend who doesn't have a computer...

1996 C220. 100K miles. Everything works except the gas guage. The dealer told him the fuel sending units were a problem in these cars. They have tested it with 2 new units and the guage still doesn't work. Is there some secret to these cars? Dealer told him this design was a problem and was changed several times.
Any suggestions? Anyone else had this problem?
I'll keep check back on here for a call to him. Thanks in advance for any suggestions!!!

[timmyj51]

Yeah, the fuel sending unit seems to be a recurring problem
with the C220. Mine hasn't worked since I had the car.
I just keep track of my gas level with the trip odometer.
Lot cheaper than spending a hundred bucks to replace the
unit with no guarantee it'll even fix the problem.

[manny]

The newer version sending units have gold-plated contacts.
This overcomes the problem caused by crappy gasoline.
If they already tried new units without success, I would suspect the dashgauge or wiring would be the culprit.

[Benzadmiral]

Mine has always been slightly to wildly inaccurate, depending on where the needle is. I fill up, and it seems to take 80 miles for the needle to even move, when it should show about 3-4 gallons gone. I filled up today with the gauge reading about 5/8 left, and it took a bit more than 7 gallons -- about a half tank.

It seems to be more accurate as I get down to 1/4 tank, but the "low fuel" light comes on with one gallon left to go, instead of the specified two.

Like you, timmyj51, I reset the trip odo, fill up before I get below 1/4, and go with that. It's a minor problem that would cost a lot more in money and annoyance to fix than necessary.

[stevebfl]

If I recall the sending units have have a 0 to 100ohm range and are in series. Substitute a know resistor and see what your readings are.