It's the ethanol in the gas that's damaging your fuel system components. We learned that lesson when Minnesota mandated all gasolines sold contain 10% ethanol in 1994.
Ethenol is corrosive. And the fuel system components in your old car were never designed to be exposed to any concentration of ethanol. You've seen the results with the float being corroded and in two pieces, and with the fuel pump diaphram eaten away.
I can't vouch if Sta-Bil for ethanol actually reduces the corrosive nature of ethanol. http://www.goldeagle.com/engine_care/411onethanol.aspx I've never had to use it because after two years Minnesota backed off it's mandate that all gas contain 10% ethanol. That's because the state was threatened with a class action law suit for mandating a law that caused damage to personal property. So we can now purchase ethanol-free gasoline in Minnesota.
Tester