Cork floats....... well sometimes!

[RMS]

i had a problem with the GTB fuel gauge, it worked ok when i built the tank but since has been showing less and less in tank eventually nothing, even after hosing £50 in, so i whipped the tank off today and guess what i found....... the cork float on the sender arm was sitting on the bottom of the tank?!?!?!?!?!? under 6 inches of fuel!

 

so what has caused the cork to sink? it was very heavy when i removed it, i tried it in fuel can and it went down like a stone!

 

i changed the cork float for a plastic one from a ZIL and bobs your uncle, gauge reading fine again. the sender unit is a Jeep repro unit by the way.

[Gordon_M]

I always expect the cork to be treated with a coat of fuel-resistant varnish. Without that it will eventually saturate ( petrol being that much more searching that water - something to do with molecule sizes and surface tensions I expect )

 

Probably easier to put a plastic float on it than to find fuel-resistant varnish these days

[antarmike]

Petrol has a lower Specific gravity or Relative density than water, so cork will always float deeper in Petrol than it would in water. It needs relatively less fluid to be absorbed before it sinks in Petrol, than it would in water....

 

Not very pertinent to this thread but I thought I would throw it in anyway....