fuel gauge always on

[52concord]

i just changed out my fuel sending unit from my 51 plymouth, the gauge is working, but the gauge stays on even when the car is off, is that okay or will it drain my battery and cause my sending unit to not last as long?

[desoto1939]

I would first check if you have one the service manual for your car. It should have a wiring schmatic for the car and it will show you how the wires are attached under the dash then check to make sure you have the wires running to and from the appropriate posts or other guages.

Sounds as if you have a hot wire running from the amp metter directly to the fuel gage.  go under the dash and find the wires.

 

Rich Hartung

[rb1949]

It should operate only when the ignition is ON.

[Plymouthy Adams]

yes it will run down the battery.....the voltage supply wire (blue) is shown on the schematic to be coming off the accessory post of the ignition switch.  It also should feed the radio through a inline fuse with a 14 amp rating connecting on the same terminal of the gauge.

[Tom Skinner]

Correct, a repair /adjustment must be made to prevent battery running down.

[maok]

The fuel gauge would use milli-amps, so the battery would take days (probably weeks) before it goes flat.