Barely took out the fuel tank to clean out the nasty black stuff in it and along with that i cleaned up the fuel gauge sender unit. It was working just fine before i took it out. Once everything was cleaned up, fuel tank, fuel filter and sender unit, i put them back together. Now my fuel gauge would only move up to the first bar which is empty when i would fill the tank all the way with fuel. How do i fix this? i suspect the ground connection is bad. My question is where is the brown wire? This is on a 81 vw rabbit pickup.