As you are finding out, shotgunning any problem is not the way to get things fixed. Just because you are not versed in electrical wiring does not mean you should spend money on other stuff "hoping" it fixes the problem. 1) If you overtightened the nut securing the send wire to the sender you may have spun the stud and damaged the new sender. If you don't have a multi-tester (Volt-Ohm-Milliammeter -- or a test light) then troubleshooting electrical systems leaves you no option other than luck at finding problems. Here is a step by step troubleshooting process: 1) Disconnect the send wire (usually pink) at the sender. Measure the resistance from the post to the shell of the sender. If it measures infinity (open circuit) or anything other than 30 - 240 ohms, the sender is bad. The resistance noted will depend on how much fuel is in the tank. 2) If the resistance measurement is acceptable, then make sure there is continuity (a good connection) between the shell of the sender and ground (negative terminal of the battery). If not, fix it. 3) With the pink wire still disconnected, check continuity of the pink wire from the tank end to the "S" terminal of the gauge. Yes -- you will likely need to extend the tester lead using another piece of wire. If the wire checks open, fix it. 4) Turn the key to ON and jumper the "S" terminal at the gauge to the GROUND terminal on the gauge. The gauge should peg FULL. If not, the gauge does not have +12 volts on the +12 volt terminal or the ground terminal does not have a good ground the gauge cannot work. Normally +12 volts and ground are simply jumpered (daisy chained) from one gauge to the next. You have not mentioned if all of the other gauges work.
