Fuel Gauge problem

[lowride]

Hi everyone. I am a curator for a collection of antique Fords and one 1964 230SL Mercedes. This car was recently purchased and I have been tracking down and repairing various problems since. My most recent problem is the fuel gauge. I am first off, confused as to which sending unit I'm supposed to have in the car. The one I have is the float inside a cylinder. Is this the correct unit for my car? (Ser#11304270004247). Next, my problem; Sending unit (new) outside of the tank and connected and grounded, my gauge on the dash reads about 1/4 full when the float is at the bottom of its travel, when I tip the unit to position the float at the top of its travel, it reads empty. 1/4 full is the maximum reading I get on the dash gauge. I believe the dash unit is functioning properly. Can anyone give me any hints on diagnosing this problem? Thanks for any help!

[geezer]

Maybe your sender is like mine.  I have a 280SE.  The sender in my car has 2 circuits.  One that turns on a light when gas is getting low and one that is for the dash indicating unit.  Did you short between ground terminal on the plug terminal G on the harness to see that the dash needle moves to full shore between ground & WC to see that the light goes on?  The contacts on the sender are WC for the warning light, G for the gauge, and the ground symbol for ground.  If I read the VDO chart correctly the resistance between G and the ground symbol should be about 66 ohms.  If the sender is rusted up inside the float may not be able to rise to the top.  You can remove the aluminum tube by unscrewing the itty bitty nut on the bottom of the sender. 

[al_lieffring]

i found a resistance table for the lever style float sensor, the canister type should be fairly close to these values

empty  10+4 ohms
1/4      50+5 ohms
1/2     100+5 ohms
3/4      143+6 ohms
full       180 +12 to -2 ohms

Hope this helps 

[Naj ✝︎]

I think your car should have the earlier 'swimmer type float' sender unit.
The sender unit you currently have came in after Chassis # 042  x0 008954, and 042 x2 013303.

The Fuel Gages on the Dash are matched to the sender units and are not interchangeable.

More info in the wiki:

http://www.sl113.org/wiki/Fuel/SenderUnit

naj

[al_lieffring]

A new fuel sender comes with a shipping pin, did you remove this before plugging in the new semder to yest it?

[lowride]

I kind of had the feeling that perhaps I have the wrong sender in the tank. I also believe that the earlier type is no longer available. Does anyone know where I can get the earlier type of "swing arm" sender?

[lowride]

More information for some help; Initially I thought the dash unit was going to full when grounded. I just noticed that the dash gauge goes to full when i merely disconnect it from the tank unit and turn the ign on (no jumper in place). Is this normal?

[al_lieffring]

No that is the opposite, open circuit should read as empty. grounded should read full Both styel of senders work this way.

[Naj ✝︎]

I kind of had the feeling that perhaps I have the wrong sender in the tank. I also believe that the earlier type is no longer available. Does anyone know where I can get the earlier type of "swing arm" sender?

http://cgi.ebay.de/Tankgeber-Hebelarm-Mercedes-230SL-W113_W0QQitemZ290337368088QQcmdZViewItemQQptZAutoteile_Zubeh%C3%B6r?hash=item439974a818&_trksid=p3286.c0.m14

naj

[Dave Gallon]

I just verified that the 230SL in question should have the earler version fuel lever sender. Part number 111 542 05 04 replaced by 111 542 11 04. It is not available from Mercedes. The auction Naj pointed us to is very promising!