Hope one of you experts can help me with this one.
I have been having some strange behaviour from the gas gauge in my 66.
No surpirse there I know. When I got the car the gauge was dead the
whole time. I replaced the sending unit which is sending fine (checked
variation in resistance) but still no change. Changed the constant
voltage regulator exactly as it was previously mounted on the back on
the instrument panel - attached to the metallic back plate of the
instrument panel via a small screw. This made no difference either
despite there being 1/2 - 3/4 of a tank of gas in there. All other
gauges seem to be fine.

Now here is the strange thing. Last night I was looking at it again and
noticed that if the constant voltage regulator is NOT screwed into the
back plate of the instrument panel, i.e insulated from it, then the gas
gauge springs to life. Unfortunately the TEMP and OIL gauges then max
out constantly. Also on the screw that attaches the regulator to the
back plate there is a male tag and a black wire running from it that
has been cut by the previous owner - looks like it has been connected
somewhere - maybe an earth ????

Can anyone please tell me exactly how the regulator must be installed
for correct performance and what this black wire is there for because
it is driving me mad???

many thanks.

Jonathan