Fuel Gauge

[tkrphxr]

Hi I am helping a buddy get his C3 going and we are having trouble with the fuel gauge with the tank full the gauge showed full. We grounded the sending unit wire and it would go to about the 3 o'clock position. Taking the wire off the sending unit would bring the needle down to between 3/4 and full. Tried resetting the pointer but no help. The sending unit reads 48 to 50 ohms with the float at the full position. Being the dummy I am we didn't check it at the empty. The gauge itself reads 48 ohms. I don't know what to try next and we haven't been able to find a replacement gauge. Help please. Thanks Charlie

 

[KenSny]

I just repaired my sending unit. The NCRS site has some good threads on this. Basically the sending unit should read 0-90 ohms. The sending unit does not need to be grounded to the car - but you must have clean connections between both sides of the potentometer (lousy spelling - sorry). Normally this "ground" side is just to the metal cover of the sending unit/filler neck. The sending unit pot and get a lot of varnish from the gas of the years. Mine just needed to be cleaned and it worked like new again. When I took it apart it read 18-100 ohms and after it was 2-88 ohms - close enought.....

 

[tkrphxr]

Thanks Ken I'll give cleaning it a shot. I did forget to mention it's a 75 model. Sorry to be so slow in replying I've been trying to get my 86 ready for spring also. Thanks again Charlie

 

[KenSny]

Well now...... Since it's a '75 (like mine) you will need to drop the tank to remove the sending unit since it's on top from our years on..... Maybe the internal bladder is starting to collaspe also. The bladder is a big problem for the 75-77 cars as it is not a very good design. GM changed the style in '78.