Hi

I am having an 88 W124 260E, and I am having a flickering fuel gauge. The flickering usually occurred when the gauge is reading three-quarters or below, and not at full tank.

What I have noticed is that the flickering will usually happened when I am pressing the accelerator. Whilst cruising constantly at about 60km/h, there wouldn’t be any flickering. When I pressed a little harder on the accelerator, the needle will flicker.

I have also noticed that flickering will usually occurred when the car is engaged in gears (D) I have tried stepping on the accelerator whilst I am in Neutral (N), and the fuel gauge needle will not flicker.

Anyone knows the cause to this flickering? Any assistance is appreciated.

Thanks :)

Lim

I have a '88 300E that has the same problem. If you do a search under fuel gauge or fuel sending unit, you will find all kinds of threads on this topic. When I inquired, it was suggested to be the fuel sending unit. Appearently this problem is quite common.

I agree with esm6869. Mine had the same problem, and it was traced to the sending unit. It is a problem with these cars, and maybe some other models...

Mine too
 

My 1992 500E does the same thing when below 1/2 tank of gas....at 125K , I should probably switch it out. How much of a pain is it to do?

Mine did the same. I kept the car full for a month straight (I had to fill it up every day) and the problem would stay away for a few months at a time. It was a cheap fix!!!

My 1991 300E had the same problem. I fixed it by replacing the sending unit. In my model it took about 10 minutes and the price/shipping time from this site's parts store were both very reasonable.

My 126 has the same problem too - though not so frequent.

The mechanic said not to worry about it, implying its a common problem as demonstrated by the vast experience here.

However, if you're persistant to tackle this problem like I was at one stage - then get someone to check the earth-wire. This could be a tricky job in dismantling the instrument panel and running the earth wire test.

You can test
 

Brother of The Benz, Lim
All replies say they too experience similar fuel gauge instrument indications.
There was no reply as to testing which unit is at fault, either the sending unit or the dash gauge.
Simple!!!!
Disconnecting the sending unit wire to the dash unit, and grounding it; the dash unit registers FULL.
If other than FULL the dash unit is at fault.
This leaves the sending unit as the faulty item.
On a W124 chassis it is easily gained access to.
Remove the inner trunk lining toward the rear seat cushion and there you'll see the fuel gauge/pick-up unit.
Obtain help via a chassis manual.
Happy Trails Beep Beep from The Spiderman in Houston!!!

You can actually just clean the existing sending unit (the string) with an SOS pad. That's what I did and mine is as good as new.

That's A Gooder
 

Brother of The Benz, Lim
You can see there are methods to correct the sending unit's problem should that be the problem child.
Read DSinger's remark about serving the sending unit!
Happy Trails Beep Beep from The Spiderman in Houston!!!

Fuel gauge not working properly
 

I thank you for posting how to test whether it was the fuel sending unit or the gauge. I already replaced the fuel sending unit and that did not correct the problem. So now i know what to do to check and see if i installed a bad sending unit or it is just that, the fuel gauge. Thank you!!

my 89 300 ce has been having the same issues,the fuel guage flickers up and down,ive reserched it and the problem in most cases has been narrowed down to a defective sending unit,it should be ok the problem ussually goes away,it only happens very rarely,if its bothering you get it checked,remember intermitent issues are hard to diagnose,but you can always have your sending unit replaced.

clean your sending unit
 

very common problem
usually fixed by buying sender- not cheap
however can be cleaned. sender is a float on a string inside a cylinder. take off 2 screws on top of cylinder and get it apart. carb cleaner on the string

cleaning will suffice
 

I replaced the sender unit and the fault was rectified . Opening the old unit and cleaning the delicate resistance wires cleared out the non conducting portions that cause the flicker. Re-installed it works fine.
I believe some fuel additives aggravate the flickering on old units .
mak

hey mak
i think that you may be on to something. my fuel gauge started behaving erratically after adding fuel injector cleaner to the tank.(about a week after) :) kinda pissed me off, but when it gets a bit warmer i plan on picking up contact cleaner or a carb cleaner and giving the sender unit wires a cleaning.

when you went to clean your fuel sender unit wires, what did you find? was there actual debris/crud stuck on the wires or was it something else? how do we identify the non-conducting portions,what should we be looking for ? did you use any abrasives on the wires other than the carb cleaner, fine sandpaper or steel wool perhaps?

thanks

just in case anyone reading hasnt found how to clean the fuel sender unit, here's the diy link : http://www.peachparts.com/Wikka/W124FuelSender

thanks jeremy an mak