Description: After about 30 years of faithful service, my fuel tank sending unit quit working. In a second generation Firebird (70-81) this shows up when the gas gauge reads past full no matter how much fuel is in the tank. Seldom, if ever, is the gauge in the dash at fault. It's easy to verify that the gauge is working by disconnecting the wire from the tank (the connector is in the trunk, by the tail lights) and grounding the gauge end to chassis. If the gauge is good, the needle will swing to "E" right away. When I confirmed that, I knew the tank had to come out so I could get at the sending unit.
I started the job by just trying the bolts holding it in. To my surprise, they came out quite easily because they had been covered with undercoating, and then rustproofing, back in the day. I actually got it out much sooner than I'd planned (as I was working alone, and it's a little tough to catch by yourself!).
It was covered on the bottom by the rustproofing, which was nearly impossible to remove. Few things in life are forever, but Ziebart comes pretty close. A pressure washer (3000 PSI, used correctly) proved to be nearly ineffective. I had to resort to using solvents to turn the rustproofing into a gooey mess, then wiping it off.
Once I cleaned the tank off, I was very surprised that it had very little (almost no) rust on it. The inside looked new and the galvanized surface wasn't even discolored. The sending unit had simply quit working because a solder joint had been attacked by the gas vapors.
The obvious solution to the sending unit problem would be to buy a reproduction or new one, but they don't make them for 74/75 F-bodies any more and the reproduction places don't have them. I finally decided to send it to Year One in Atlanta to have the original rebuilt. In the meantime, to keep the car running, I stuck in a salvaged one from a 75 Firebird that I didn't think would last long. It seems to work so far -- for how long, I dunno -- but it does for the moment.
I painted the tank with Tank Tone by Eastwood, then reinstalled it. After sticking a little gas in the tank and priming the carb, it fired right up.
In another week I will have the AC recharged (I have the new hose/muffler assembly it needs in hand) and in the meantime I intend to do a little chassis detailing around the rear end. I've already done the traction bars -- that will be another album.