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Discussion Starter #1
I am new to this.

I seached for and followed the post below to take out the fuel sending unit and cleaned it with brake parts cleaner.

http://www.benzworld.org/forums/w123-e-ce-d-cd-td/1401434-cleaned-fuel-sending-unit-today.html

When I re installed the unit, the gauge on the dash does not read anything. The unit had a lot of bulid up on it and was restricting the float from moving upward. The float now moves up and down.

Prior to this the unit would move from just ove 1/2 to about 1/4. I never let the tank get to low of fuel so I am not sure on the full range of the gauge prior.

I checked the contectors on the top of the Fuel Sending unit and they look fine.


Thanks
 

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1980 Mercedes 240D, 1988 Acura Legend Coupe 5MT
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13 Posts
Are you sure that the float is following the three little metal wires all the way up and down?

Also just wiggle the wires and connector with the key in the on position to see if it starts reading. It sounds like a connection issue.
 

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'89 300TE, '79 450SL, '01 ML320
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1,051 Posts
Did you clean and replace the discs on the bottom correctly so that fuel is able to enter the tube?
Fuel has to be able to pass thru that 'maze' in the bottom, also be sure it's not sitting in a
pile of tank mud in the bottom of the tank :)



Fish
 

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2014 Mercedes-Benz GLK250 Bluetec, 1981 Mercedes-Benz 300D W123
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600 Posts
Sorry to drag up an old post. But my sending unit was having some issues it would ALWAYS read a little bit lower that half a tank. So I removed the sending unit. Sure enough, the shaft in the middle was rusty. I used brake cleaner on the entire unit as well as electrical contact cleaner after sanding the center shaft down to bare metal. Made sure everything was SUPER clean including the aluminum tube, the shaft, the wires, the connection on the top and the metal plate and nut at the bottom. I lubercated the center shaft with some 3 and 1 oil and made sure that it moved up and down smooth as butter. All three wires strong connections and were not getting bound up at all. I matched the notch up at the top of the tube and placed the sanded and cleaned metal plate over the cleaned out maze end and put the nut back on snugly. Put a little oil on the oring and screwed it back into the tank. Plugged it in. Started the car. No reading. Empty. The reserve light come on when I first turn the ignition as it always has. Then it goes out and the gage reads nothing. Am I'm missing a step? Could the wires have become someone entangled when I placed the unit back in the tank? Or does it take a long while for all of the air to get out of it? Also take note the my tank is full to the brim. Sorry to drag this post back up but it seems to be the closest post with my issue. Thanks.
 

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1985 300TD On the road! and too many Dodges to list!
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367 Posts
Watching this thread. My gauge in my 82 300td works sometimes and sometimes not. :(
 

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77 240D
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993 Posts
if the movement of the floater provides the tank level reading, what informs the red low fuel light? I haven't taken mine apart yet.
 

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1979 240D
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949 Posts
if the movement of the floater provides the tank level reading, what informs the red low fuel light? I haven't taken mine apart yet.
There is a contact at the bottom of the sender, when the float touches the bottom it activates the light.
 
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