I just got in on this fuel sending unit story. Do you have the ground strap that clamps to the fuel line at the tank and the fuel that is in the fuel sender unit. It clamps on at both ends and they are different lengths. I have these new in two lengths.
Were you able to check the new senders? It can be done if you have it out of the tank by putting a ground wire from a ground on a battery. Then put a light testor to the disc that the metal lines run thru and you will have a dim light when the float is at the low point. Raise the float arm up and the light will brighten as you raise it. Or, you can just remove the wire to the sendor and put a test light to it and ground to the car. Then turn on the key to either accessory or run mode without starting. Check to see if the testor lights up. This second way will not allow you to see if the light gets brighter though as the float cannot be raised while inside the tank. joe machado