Gas gauge 1954

[Ted K.]

Replaced the gas tank and now replacing the old sending unit. When I attach the wires to the sending unit and turn on the key I get no response on the fuel gauge when moving the float up and down. I checked the voltage at the sending unit and it is 3 volts. Is that what it should be? Seems like it should be 6 volts. Any tip on trouble shooting the gas gauge?
Thanks

[Dan D.]

Re: Gas gauge 1954

Ted,

Should be near 6V with the float all the way up (full tank) and zero with the float all the way down. Do you have the sending unit grounded? Needs to be in order to work. If you are using the tank ground wire make sure it is a good ground. They are famous for corroding up and not at a good ground potential.

-Dan-

[Ted K.]

Re: Gas gauge 1954

Thanks, the 3 volt reading was between the hot wire and the ground without being attached to the sending unit. I assume it should be 6 volts before it gets to the sending unit. Would that be an indication of a poor ground?

[Dan D.]

Re: Gas gauge 1954

Ted, if you leave the sending unit disconnected the gauge should go past full. If you ground the sending unit wire the gauge should go to empty. But do not use the sending unit ground lead as that may not be a good ground at this point. If you do not pass this test, then the gauge is not working. Connect your ground wire to battery ground if possible, or to the engine. Also, measure the ground wire with an ohm meter. It should be at or near ground potential.

-Dan-

[Ted K.]

Re: Gas gauge 1954

Dan, According to the ohm meter the ground wire at the sending unit end is a solid connection to ground. I went under the dash with a volt meter and have 6 volts going to the fuel gauge and only 3 volts at the other terminal of the gauge with the sending unit not attached.

[Dan D.]

Re: Gas gauge 1954

Ted, I am not certain that 3 volts is wrong at the fuel gauge. Don't remember real good about 6 volt systems. Perhaps someone more in the know can advise on this.

But for sure, with the sending wire disconnected at the fuel gauge, the gauge should read past full. Then try grounding it and see if it reads empty.

Also, a 12 volt sending unit should read 30 ohms at full and zero at empty. I think 6 volt systems should be similar.

-Dan-

[Ted K.]

Re: Gas gauge 1954

Thanks, something to do Monday.