I have no knowledge of that specific vehicle, but if the needle is
pinned when the ignition is on and the engine is not even running I'd
think a short somewhere. I'd pull the connection off the pressure sender
and see if the needle dropped. If it did I'd replace the sender, if not
just start tracing the wiring back to the gauge.

If it only is pinned when the engine is actually running, particularly
if it takes a second before it pins, then I'd suspect a serious clog
somewhere in the engine oil galleys and I'd not run it until it was
thoroughly inspected.

Pete C.

Had this happen to 63' ford Galaxy I was just finished restoring.
Anyway what happen was I was driving down the road and looked at the
gauges, everything fine, next time I looked five seconds later and the
gas, temp, oil gauges were pegged. My first thought was "HOLY CRAP"
I thought I had a big time short somewhere but it turned out to be the
Constant voltage regulator for the gauges. Your car may use one. My
63' was easy to find
It was on the back of the cluster, looked like a very small relay. You
may have to make a trip to the library and look at a Mitchell Manual
wire Diagrams for your car.

Let us know what you find out, Rick

Thank you for your reply. I disassembled the dash, then the cluster and put
it back in place with my finger, I then cleaned all connections and "walla",
it now works. Thanks fellas.