Fuel Gauge Reading

[amphi662001]

Over the years I have had the "opportunity" to replace Amphi's sending unit
several times as the windings wear. However, the gauge always reads about 1/4
tank low. The sending unit arm has full travel and checking directly w/ an ohm
meter seems to indicate the windings are proper which makes me think
1. the gauge itself is bad,
2. there is an improper ground somewhere I can't find, OR
3. there is a know Amphicar gremlin that isn't posted on escribe!

The gauge will read full if shorted to ground.

Obviously this doesn't affect operation in any way, but it is a puzzle. Any
suggestions from the vast depository of Amphicar lore and knowledge out there?

Thanks, -LarryS

 

[John Friese]

Hello Larry,
I've switched many Amphicar gas gauges over to negative ground and, in
the process, learned quite a bit about them. There are calibration
adjustments that have to be made when you do such a conversion if you
want to have the gauge read correctly. There are two coils inside.
One is adjusted for a correct "full" reading and the other for
"empty". If either are out of adjustment, the gauge won't read
accurately although, given the flatness of the tank, there's only so
much you can do. The sending unit is of a 10-180 standard type, which
means 10 ohms at one end and 180 ohms at the other. The sending units
I've seen actually read about zero at one end and 180 at the other
but that's okay. I did come accross one gauge that simply wouldn't
calibrate. I suspected that a partial short existed in the coils
since, when I switched the coils with another gauge that had a broken
pointer, it calibrated correctly.

John Friese




--- In amphicar-lovers@yahoogroups.com, "amphi662001
<amphi662001@y...>" <amphi662001@y...> wrote:
> Over the years I have had the "opportunity" to replace Amphi's
sending unit several times as the windings wear. However, the gauge
always reads about 1/4 tank low. The sending unit arm has full travel
and checking directly w/ an ohm meter seems to indicate the windings
are proper which makes me think
> 1. the gauge itself is bad,
> 2. there is an improper ground somewhere I can't find, OR
> 3. there is a know Amphicar gremlin that isn't posted on escribe!
>
> The gauge will read full if shorted to ground.
>
> Obviously this doesn't affect operation in any way, but it is a
puzzle. Any suggestions from the vast depository of Amphicar lore and
knowledge out there?
>
> Thanks, -LarryS