I'm having trouble with my fuel gauge in my 69 camaro, 350 auto. The old gauge has a resistor on it but the wire is broke so dont know if it ever worked. Bought a new gauge,oem, suppose to have resistor built in i was told and hooked it up and it goes from e to full and half way past that like its reading upside down. have new underdash harness installed with one ground on center dash brace and one on bottom of carrier. ground is in trunk on inside but still reads messed up, any suggestions???