gas gauge 1939 tonner

[1939 dave]

what should be the voltage at the connection on sending unit with the wire disconnected?

[JSeery]

On the connection itself? zero, it is a path to ground. The current flows from the gauge in the instrument panel to the sender to ground.

[1939 dave]

I installed new sending unit, gauge not showing anything truck has been sitting for 35 yr. don:t condition of gauge itself any ideas

[tubman]

Same old problem. Ford gauges use the "King-Seeley" system which works differently from most other systems. Most (probably all) replacement sending units are the resistance type and won't work well in Ford systems. Touching the wire to ground should make the gauge move. If it doesn't, either the gauge or the wire to it is bad. Try a jumper from the terminal on the gauge to ground. No action, the gauge is bad; if the gauge moves, the wire to the gauge is bad. Only touch the wire to ground for a short time or you will have other problems.

[JSeery]

I assumed we were talking original here, see that is not the case! Still zero at the sender connection, but it will be a resistance unit.

[tubman]

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Originally Posted by JSeery

I made the assumed we were talking original here, see that is not the case! Still zero at the sender connection, but it will be a resistance unit.

He said the truck has been sitting 35 years. I don't see what is wrong with your original assumption.

[19Fordy]

Will this little pictorial help in checking your set up?

[alanwoodieman]

run a ground wire from one of the screws holding the gauge to the tank to a good clean location--grounded mine to the cab back wall with ign on, if you momentarily touch the gauge wire to this ground does the gauge on the dash work?

[KGS]

Originally Posted by 19Fordy

Will this little pictorial help in checking your set up?

Should be positive ground for the 6 volt system on the Ford. Yes?