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I've noticed over the past couple of months my fuel needle occasionally flickering when the tank is between then 1/2 and 3/4 full level. Doesn't do it when full, or much below the halfway mark (as others have experienced over the years). And it's not enough that makes me think that it's reading inaccurately, but I'm seeing some flicking of the needle back and forth (actual to just below the 1/2 point) while driving down the road.

I think the issue with this is probably a gunked-up fuel sender unit (the wires that run the length of it that measure fuel level), rather than a ground/electrical issue. I'm going to pull the sender in the next couple of weeks and carefully clean it, and will report back my process and results. Perhaps put a diagnostic up on the wiki as well.

If anyone has any tips or tricks on this, or has done it before, I'd love to hear anything you have to say on the matter.

Cheers,
Gerry

Their is a write up of this on the Mercedesshop. I think its in the DIY section.

I have this issue too, but didn't bother with it yet, it only occurs in cold weather.

regards

I had the same problem (fluctuation and flickering) too but now the needle is totally dead. Previous owner replaced the fuel sender unit with no results. I can't replace the fuel indicator because it's no longer aviable so I'm planning to take it to a specialist to fix it. I'll let you know if they're able to solve the problem.

Interestingly, this condition has totally disappeared from my car, and the fuel needle is acting 100% normal since probably last fall. Go figure.

Cheers,
Gerry

I don't know of any way to open the sending unit and clean inside, but the problem is usually either the sender or the gauge itself. I had a similar issue on two different W124's and in both cases it turned out to be a bad gauge... I have the issue on a third car and I think on that one it is the sender (just replaced, will know if it's fixed after I run a tank of fuel through it - UPDATE - yes, the new sender fixed car #3).

A new 500E fuel/oil/temp gauge is spendy, and of course it's specific to the 124.036 chassis. However a standard F/O/T gauge from a .032 or .034 chassis can be recalibrated to work properly with the .036 sender if you know how to do it. BT, DT.

A description of the fuel gauge & sender, including specifications & troubleshooting, is in the FSM at these two links:

http://www.ps2cho.net/downloads/MB%20CD ... 4-0256.pdf

http://www.ps2cho.net/downloads/MB%20CD ... 4-0257.pdf

I finally disassembled mine and the circuit is totally fried. Imposible to repair. The dealer has been able to find one in germany but it is ridiculously expensive: 600€ (around 780$).

500ESpain, you can use any fuel gauge cluster from another W124 sedan with 90L fuel tank. The gauges for 90L tanks use a different sender (with yellow top, as seen on the 500E) which have slightly different calibration specs, as noted in the links I posted above.

You have three choices:

1) Spend the obscene 600€ for a new one.

2) Find a good used gauge, either from a 500E being parted out, or some other 124 sedan with optional 90L tank

3) Swap in a standard 70L gauge & sender from a 400E or other W124 sedan. This will still read correctly, but may effectively reduce the reserve amount; the 70L sender is 5-10mm longer and will turn on the reserve light later.


I'd go with option #2 if possible, followed by #3.

Thanks, gsxr, but the problem is that I have the onboard computer so the gauges have a different set up. I haven´t been able to find a second hand one.

Ooohhhhhh! Well in that case - ouch. Might have to fork over the 600€ for a new one then. I didn't realize you have the trip computer. Very nice, very rare option, but more difficult to repair / replace when necessary.

Yes, having the trip computer and having a 500E is nice except when it comes time to pay. But I still think the experience is worthy, anyway!