Hot Rod Forum banner

1 - 2 of 2 Posts

·
Registered
Joined
·
1 Posts
Discussion Starter · #1 ·
I have a 1949 ford passenger car which has been converted to 12 volt before I got it. The fuel gauge was working fine until about a year ago. It suddenly stopped working and stayed on empty.

So I got a Stewart Warner fuel gauge part number 82303. 2-1/16 Inch (52.40mm diameter) Elec Fuel Level Gauge-240/33 Ohm
60 degree sweep and I also got a Stewart Warner fuel sending unit 385C-F R Swing 6-12 Fuel Level Sending Unit, 240/33 Ohm Stewart Warner 385C-F R Swing 6-12 Fuel Level Sending Unit, 240/33 Ohm - Speedway Motors, America's Oldest Speed Shop

At the back of the old gauge, there are two connectors, one with a red wire attached and one with a black wire attached. The black wire goes hot when the ignition is on and the red one doesn't go hot ever.

The back of the new fuel gauge has 4 connectors, one marked "S" for sending unit, one marked "I" for ignition and one marked ground. The fourth one has no markings on it but I've taken it to an auto electrician who said it's also a ground. The fuel gauge is grounded anyway by the unit it's attached to.

My issue is this. If I attach the hot wire to the ignition connector and the red wire to the S connector then turn the ignition on, the fuel gauge shoots to EMPTY. If I switch them around, the same thing happens - shoots to EMPTY. But the strange thing is this. If I remove the red wire and connect only the black, hot wire then turn on the ignition, it still shoots to EMPTY regardless of whether the hot wire is attached to the ignition or the sending connector. In other words, the only wire that seems to count is the black, hot wire and the gauge goes to EMPTY whether it's connected to the ignition or the sending connector.

Can anyone help me wire this up correctly?
Thanks in advance
 

·
Registered
Joined
·
3,111 Posts
Typically, In Lay terms......The switched +12v goes to one side of the gauge and the sending unit wire to the other side. The gauge is always hot (with the key on) the sending unit provides the ground for the coil inside the gauge and the windings inside the gauge gets a separate, always ground. When the tank is full the sender, sends little resistance to the gauge and the needle reads full, when the tank is empty the senders sends a lot of resistance to the gauge and the needle reads empty.

Needle pegs full or past full – Break in the fuel sender wire (Tan) or tank’s ground wire is disconnected

Needle pegs empty or past empty – Break in the Gauge’s ground connection (under the dash)

Needle’s stuck in one place – Break in the Gauge’s 12v supply

My terminology may not be off but this is as simple as I know how to explain it.
 
1 - 2 of 2 Posts
Top