Re: [DML] Re: repairing OEM fuel sender & Tankzilla

["Walter Coe" <Whalt@xxxx>]

> The only time it is close to
> accurate is either when you are parked or travelling straight for a
> period of time on a LEVEL road.

I disagree with this to differing degrees.

The Tankzilla is VERY accurate when still and remains accurate with the fuel
sloshing in the tank IF most of the holes in the bottom are restricted. The
idea is to allow fuel to enter/exit the sender very slowly but not to
restrict the openings so much that they clog. This is easily done with a
little creative epoxy work.

The OEM sender is another issue. What makes it less accurate than the
Tankzilla is that the float moves up & down on an insulated rod that is
wrapped with a coil of resistive wire. This wire isn't always wrapped on
the rod with the best of care. Some loops of it short-circuit with adjacent
loops. If it wasn't wrapped very tight, then sections of it can sag or
bunch up. This can give non-linear readings. Also the way the float makes
an electrical connection with the resistive wire is unstable and can
contribute to inaccurate readings.

> Also I have noticed on many cars the
> fuel gauge is not calibrated to operate linearly i.e. it stay on full
> way too long ang then when it does start moving it drops like a rock.

Now with typical Fords & GM cars that I am used to driving, these are
anything but linear. I always find the scale to be logarithmic such that
FULL means full, 3/4 gauge means you have half a tank left, 1/2 gauge means
you have about 1/4 tank left and 1/4 gauge means you are almost empty. (I
charted this with a Ford on a long trip. BTW, I'm a Libra, and so is my
DeLorean, Sept '81 build -- always weighing & measuring!) This is not the
case with the Tankzilla in the DeLorean. The DeLorean's fuel tank has a
linear volume vertically, and the Tankzilla's resistive wire is a tight
U-shaped loop that leaves no room for slop.

I want to see someone make a solid-state fuel sender that works on the
principle of interelectrode capacitance or perhaps sonar. I've seen sonar
setups work for monitoring fluid levels in cryogenic storage liquid nitrogen
bottles. The same concept would make an excellent fuel $ender.

Walt Tampa, FL