we dropped the gas tank on 58 chevy installed new sending unit, but prior to buttoning up we hooked gauge wires and manually moved float and gauge went to F. Put 5 gal. gas in and gauge moved just off E! Should have moved to 1/8 or even 1/4. Drained gas and manually moved float to read 1/4 and it was barely moved to obtain 1/4. Put back in and added 10 gal. just barely off E!!!! Any suggestion will be appreciated!