Erratic fuel level guage on W124 E300d

joe1972

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Hi all.

One of the last problems I haven't yet addressed with my E300d is the erratic fuel gauge.
It's forecast wet weather this weekend, the gardens just been done, so this weekend I think I'll have an investigation to hopefully find out what's going on..


The fuel level needle seems to jump all over the place, even with the car stationary. And just recently over the last day or two hasn't moved off the 'less than' empty position (ie the position the needle sits at with the ignition off).... the low level warning light is not on (ie there's about third to half a tank of diesel in there by my estimates)

The fuel warning light has always worked, and never been a problem, so I've kinda relied on that (and a small gerry can in the boot) to ensure I don't get stranded somewhere.....

Is the fuel level needle and low level warning light on different circuits?
Should I pull the fuel tank sender connection off, or should I start at pulling the instrument cluster unit first? (the oil pressure needle has flickered in the past too)

What do people think this might be?
Are there any common issues I should look out for?

would welcome some thoughts and experience.
thanks
 
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television

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Most faults are on the float in the tank. there are 2 circuits as such, the float contacts are one, and when the float gets to the bottom of the tank it connects to another contact that turns the lamp on as well
 
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joe1972

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Thanks again Malcolm.
I shall be out with it in a moment to investigate.
I'll got pull the boot carpet first and leave the instrument cluster well alone for the first instance.
cheers
 

television

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I believe that if you pull the wires off the float the gauge should read full
 
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joe1972

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Work in progress update;
Just opened up and removed the fuel sender......something went 'plop' and I pulled out the three contact/white top (with two broken looking soldered connections) with what looks like a coathanger diameter wire on the end with a very small thread at the tip.....

DAM AND BLAST!
 
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joe1972

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From this link;

http://www.peachparts.com/Wikka/W124FuelSender


It looks as though what might have happened is someone has been here before me and that retainer nut was either loose or not there, and the whole lot has slipped off and fallen back off into the tank!....
I've removed the tank 4x retaining nuts and 'jiggled' the tank to and fro......yes, I think it is in there and it floats!!!

DAM AND BLAST 2
 
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joe1972

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I think realistically the tank has got to come out!

DAM AND BLAST 3

lol
 

television

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Is it not worth getting one from a breaker
 
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joe1972

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Yes, I was thinking that........It worries me that bits are left in the tank though. I'm guessing the float is naturally the only bit actually floating (that I could hear when I rattled the tank)...

What is the fuel pick up filter design like?
Would you reckon it would be ok to leave the bits in the tank and just get a replacement?....as I dont fancy removing the tank to empty it all out
 

television

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Only the plastic bits will float and they will do no harm, any other bits can stay on the bottom
 
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joe1972

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Thanks.
That make sense to me, particularly as it doesnt involve pull the tank out.
I'm thinking the bits I rescue from the tank arent going to be salvageable anyhows, so just wanted to clear up that it is ok to drive with those couple of bits in the tank.
 

television

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Any bits will stick to the bottom,diesel always leaves a residue, It will be fine, at least you will not need the spare can of fuel in the car :D:D
 
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joe1972

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Yes!....although having a small gerry can in the boot comes naturally now, and fits perfectly down the sid of the boot space, along with some coolant, and a bit of motor oil!.....(an old habit that comes with driving crappy Italian cars in my past) :lol:


thanks again...



Now....to find a working W124 fuel sender unit as cheap as possible!
 

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