1956 gauge voltage

[Jack Bowser]

My fuel gauge is reading half with a full tank.

I sent my fuel sender in for rebuild but the rebuilder tells me my sender is working fine.

I asked him about the low voltage regulator ( called constant voltage unit in the gauge circuit drawing in the service manual, page 253, figure49 gauge circuit) and he said I should NOT have a voltage regulator in the gauge circuit in 1956 because Ford used 12 volt gauges in 1956. I assumed he was right because this would explain why my gauge was reading half of what it should be reading (half voltage to the gauge gives half reading). HOWEVER....the pictorial of the gauge circuit in the service bulletin clearly shows what they call a constant voltage unit in series with the 12 volt line to the gsuges....so we have a schematic showing NO low volt regulator and a service buliten that shows one. The wire that goes to the gauges from my fuse box that is connected to a low voltage regulator is too short to make it to the 12 volt buss bar so it looks like the regulator should be there.

I would appreciate comments from anyone who knows what is correct here. Thanks

I just noticed that Service bulletin # 73 was written in 1957. The gauge repair guy told me that Ford went back to 6 volt gauges in 1957 so maybe that is why the service bulletin doesn't show the low voltage regulator. I'm determined to learn the correct setup for our gauges and hope this is helpful to everyone.

I'm at a loss why my fuel gauge is only reading half when the sender is at the full position. The temp gauge seems to be working correctly but my oil pressure gauge is erratic. Sometimes seems right and other times reads very low or doesn't seem to move at all. I've checked grounds and other obvious things. Any ideas out there? Can some 1956 Mark II owners please look inside your fuse box and tell me if you have a low voltage regulator mounted to the vertical end piece of your fuse box/ It is a small rectangular unit with 2 connections. 12 Volts and the low voltage out. The case is ground. This is on the outside of the fuse box towards the rider side fender.