52concord Posted March 20, 2017 Report Share Posted March 20, 2017 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? Quote Link to comment Share on other sites More sharing options...
desoto1939 Posted March 20, 2017 Report Share Posted March 20, 2017 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 Quote Link to comment Share on other sites More sharing options...
rb1949 Posted March 21, 2017 Report Share Posted March 21, 2017 It should operate only when the ignition is ON. Quote Link to comment Share on other sites More sharing options...
Plymouthy Adams Posted March 21, 2017 Report Share Posted March 21, 2017 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. Quote Link to comment Share on other sites More sharing options...
Tom Skinner Posted March 21, 2017 Report Share Posted March 21, 2017 Correct, a repair /adjustment must be made to prevent battery running down. Quote Link to comment Share on other sites More sharing options...
maok Posted March 21, 2017 Report Share Posted March 21, 2017 The fuel gauge would use milli-amps, so the battery would take days (probably weeks) before it goes flat. Quote Link to comment Share on other sites More sharing options...
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