My old tractor had a very simple gas gauge, which had few moving parts and
no electricity in the fuel tank.  Easy to hack to an electronic sensor.

It had a float which ran up and down two parallel rods.  Friction with the
rods helped dampen sloshing , and it was near the center of the tank, which
might get less sloshing than the extremities (??)

The float had a slot in it, which drives a flat piece of steel that is
twisted into a spiral, maybe 3/4 turn.  The end of the spirally-twisted flat
had a rod welded to it, which sticks through the top of the sensor. The
spirally-wound flat is free to rotate around it's long axis.  The whole
thing was attached to the inside of the tank's fill cap, which made it easy
to remove and clean.

As the float goes up, it drives the spiral right.  As the float goes down,
it drives the spiral left.

The rod coming out of the top ran a little mechanical gauge, but could also
easily run a potentiometer.  I notice most gas gauges respond VERY slowly,
like over minutes' time, to eliminate sloshing problems.

Don't hack electric stuff inside your fuel tank.  This is done by the pros,
with VERY CAREFUL design and testing, limited energy wiring, special
coatings, materials and so on.  Yes, we are all pros, but this is something
to avoid.

--Lawrence Lile

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