Author Topic: Loopy fuel gauge  (Read 1233 times)

olliparr

  • Enthusiast
  • *
  • Posts: 36
  • Location: Netherlands
Loopy fuel gauge
« on: 01 May 2006, 02:22 PM »
 :-\ The needle on my fuel gauge has been swinging around pretty freely recently - today it sold me a quarter tank dummy and left me stranded.  >:( I live in Holland so hills are not to blame - oh and the fuel gauge low warning light doesn't work. Heard rumours that the tank float can rot leading to this eccentric behaviour. Can it be replaced? Does anybodt know the system for the fuel gauge - ie. is it an iron bar/bimetallic/air core etc? Why is it always raining in Holland?

Denis

  • Classic
  • **
  • Posts: 334
  • Location: Paris
Re: Loopy fuel gauge
« Reply #1 on: 01 May 2006, 02:40 PM »
G'dag Olliparr

I happen to know that in the middle of Holland, there are a few waves in the terrain that might be construed as hills by Dutch standards  ;D

The fuel gauge is an amazing device : a metal float moves up and down in a cylindrical chamber. As it does, it makes contact along two conducting wires going from the top to the bottom of the cylinder. When close to the top, there is little resistive wire to make the circuit to the connector, at the top, when at the bottom, ther is a lot more. The resistance is made up of the wire going down, through teh float and back up to the top. The resistance varies and that is what is read by the gauge. The warning light is another contact at some point when the float is nearing the bottom. There is nothing that can rot there but it can get quite dirty or worn and its conductivity can become erratic, making the needle move to bizarre positions.

I have actually removed one, taken it apart, carefully cleaned it and put it back in service. And then there was the time I tried this on my 6.3, and failed. So I bought a new one. It turns out that the sensor was unique to the 6.3 and I still remember paying 206€ for it  :o

Normal ones are about half that price and salvage yards can be an even better source.

It always rains in Holland because the french military have invented a secret weapon fan that blows our own miserably wet northern france climate towards the Zeeland  ::)

Hope this helps

Denis

Paris, France