61 fuel gauge

[WOW-WEE]

I have a problem with my fuel gauge-darn thing stuck in the full position.
I just replaced the sending unit but to no avail. Even when the ignition switch is off the fue indicator reads full. I took the gauge out and seems to be operating correctly-indicator moves. When i put it back together and put the ignition key on it returns back to the full position. Please help before i'am found on the the road dead-FORD.

 

[JohnZ]

A constant "Full" reading with the ignition on indicates high resistance in the circuit, as you would find if the sending unit wasn't grounded properly. When you replaced the sending unit, did you connect the ground lead? That ground is shaky anyway, as it's shared with the rear lamps at the left rear corner of the trunk - I always add a dedicated ground wire from the sending unit directly to the frame, right below where the fuel line exits the tank compartment.

Easy check for the gauge - disconnect the brown sender wire at the gauge, and it should show "Full" with the ignition on; with the sender wire still disconnected, connect a jumper wire from the sender wire terminal on the gauge to ground, and it should show "Empty" with the ignition on. The sending unit is between the gauge terminal brown wire and ground; it has zero ohms resistance with the tank empty, and 30-33 ohms resistance with the tank full.