The fuel lines are different depending on your engine and carb set up so I am limited in what I can do to help. The sending unit requires a ground to work, so make sure the ground wire is in place. My sender connects to the main fuel line with a short piece of rubber fuel line. If your is the same, make sure the line is not kinked. The tank requires a vent to function correctly. Mine comes with a vented cap. You may need to blow compressed air in the main line to free an obstruction. Make sure the fuel pump is disconnected,and you blow the air in the other end of the line, NOT in the tank.If all else fails, then down comes the tank, and a check of the sending unit itself is required. The sending unit itself is simple. Check the pipe for free flow and check the reostat with an ohm meter or test light and separate power source.