shoeless,
No replies yet, so I will give it a try but I am no expert on this one (though I have experienced and diagnosed every problem below - except frying a 6v guage with 12v current).
Your profile says you have a 1952 half-ton Chevy.
First, if you are using the original gas guage, use a correct voltage reduce (I think it is called a Runtz resistor) on the side of the hot lead..
It looks like you are going step-by-step in testing things out. You can check out the guage (without the sender lead in place) by giving it current (yes, it gets current when the ignition switched is turned on). The guage should peg to Full. If it does not, you might not have current going to the guage (easy to check), you might have a poorly grounded guage cluster case (run a good lead to the case and see what happens), the guage might not be grounded to the case (a little harder to trace this back unless you are bench testing the guage cluster), or you might have a bad guage unit (12 volts without a resistor can fry the guage).
If the guage pegs to full, you could then move on to connecting the sender unit lead and proceeding with a new set of tests.
If any of the above is wrong, incomplete, or poorly described, someone will post better advice.
Good luck,
Tim
