87 300E Fuel Gauge fluctuate
 

Hi:

The fuel gauge at times starts fluctuating when the gas has about 1/4 tank of fuel left and sometimes the needle would indicate the tank is empty and the warning light would come on. When that happens, the needle at the economy fuel indicator ocillates back and forth. It's a nuisance otherwise the car runs fine with 15K miles and gets about 18 miles per gallon so I have to remember to fill up the tank when it reaches 300 miles after last filled up. Any advice?

DL

The problem is likely corrosion or dirty contacts in the fuel level sending unit that is inside the gas tank.

First suggestion: Try a good fuel detergent additive (like Chevron Techron) and see if that does't help before going further. That solved my problem.

Thanks., I'll certainly try it first. By the way my car has 150k miles on it not 15K on my original post.

same thing with my 260E as well. I use the techron chevron on a regular basis but that didn't help the needle fluctuation.

It's probably deposit buildup on the wire wind because the gage may not get that low very often if you are in the habit of filling up before it gets to the quarter point.

Pumping in a few gallons when it is near empty several times will excercise the wiper between empty and a quarter and it may rub of the varnish.

This worked for me - for a while at least. I've removed sending units from GM cars and cleaned the wire wind, but I'm not sure if the MBZ sending unit can be disassebled enough to get to the varnish.

Anybody know?

Duke

Don't know - but the sending units are not that expensive - $30-$35, and are easy to put in. I wouldn't spend too much time fixing the old one.