gauges swinging

["Scott Johnson" <scott@domain.elided>]

Many years ago I reported the exact behaivior that Scott Fisher is reporting. I
was told by several "old timers" that I wasn't seeing what I knew I was seeing.
Glad to know this is a mass halucination...

The gas gauge vs. the oil gauge thing I think I can explain. It would seem that
the early model 105/115 spiders do not have baffles in the gas tank. Or at least
not very effective ones. You can even hear this by getting the car to move
fore-aft suddenly and then listening. The distinctive "slosh" of the gas will be
clearly heard. 

The gas gauge sender is nothing more than a fancy version of the cork float-type
units I used to find in my dad's motorboat gas tanks. It is quite free to move
in its travel in response to surface movement of the fuel.

What happens is when the gas gets low, it really starts to move around in the
tank. This bounces the sender around (and will eventually wear the sender out,
but that's a different post), and this is what causes the needle to swing so
wildly.

The oil pressure sender works on a different principle (electrical resistance?),
so it doesn't respond the same way. 

Hope this helps!

Scott Johnson
Alfa Spider FAQ Author

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