Have you confirmed the ground wire is good with a ohm meter?
Have you tested the sending unit with a long temporary ground jumper wire going from the battery negative terminal to the mounting screw on the sending unit?
Mike B
Mike Boteler
1956 Chevy 3100 Resto Rod 1952 Willys M38 Army Jeep 1983 Jeep CJ7 Laredo 1984 Jeep CJ7 +++++ Silver Spring, MD