I think (but am not sure) that Pontiac had changed to a zero ohms empty, 90 ohms full by 1965. Earlier systems were 30 ohms full.
In either case, remove the wire from the sending unit, but leave the gas gauge end of the wire attached.
Turn on the key.
Touch the sending unit end of the wire to ground. The gauge should read empty.
Let the sending end of the wire dangle in free space. The gauge should read full.
If both are correct the wiring and the gauge are good.
If you have an ohm meter you can measure ohms with one meter lead on the post of the sending unit and the other lead on the mount of the sending unit. Should read zero ohms when the float is all the way down, about 45 ohms with the flot half way up and 90 ohms with the float "full".
__________________
My Pontiac is a '57 GMC with its original 347" Pontiac V8 and dual-range Hydra-Matic.
|