Gas gauges on A-bodies

mvh said
On a 67-69 A body rally dash (Barracuda) the fuel gauge includes the instrument voltage regulator. If this fails, it quickly burns out the fuel gauge and possibly the oil pressure gauge. Other A-bodies have a separate instrument voltage regulator, and since they usually have a idiot light for oil pressure, it is only the fuel gauge that is affected. This is probably more common than a sender failure.

The other common failure mode is the loss of the ground strap from the the sender unit to the hard fuel line. This is a sheet metal clip and it can rust or break from fatigue.

On ‘67-76 A bodies with the standard panel, the voltage reducer (12v->5v) powers the fuel and temp gauges. If it fails dead, both stop working; if it fails “hot” both gauges peg and will burn out shortly (ask me how I know!!). However, they are surprisingly reliable (my original worked for over 25 years). Solid state replacements are available which not only are more reliable but provide a much more stable output. It’s one thing to consider as a source of trouble but unless you are seeing the failure modes I just described it probably isn’t the cause.