1965 Mustang coupe
Water certainly would have condensed over that time. Did you put any Stabil in the tank? I'd run a bottle or two of dry gas or Seafoam to get rid of the water.
Simple dry gas is nothing more than alcohol and will absorb water. It won't foul your plugs. Stabil is fuel stabilizer that keeps it from turning to varnish when sitting for an extended period.I've never put anything in the gas. Do you know how the stuff works or is it just magic?
One thing while we're talking Stabil. It doesn't work on old gas. You need to add it when the gas is fresh. Once it starts to varnish, Stabil does no good. That's when I'd use Seafoam.Sorry, I got to talking Stabil and didn't offer any advice. The bad gas has to go. Mixing higher octane will help some, but DO NOT TUNE with old gas in the tank. Burn it off or drain it. I would also recommend fuel injecter cleaner run through the system as well. That will disolve any varnish that formed in the tank and is now flowing through the rest of the fuel system. After this tank is gone, buy 1/4 tank and use the fuel injecter cleaner. That stuff works well and 1/4 tank will clean averything out.
Tough to drain a two side tank completely without removing it.Drain it. When I switched from 87 to 93 i used a drill pump and pumped all of my gas into my F-150 and then filled the GT up with nice fresh 93 shell. Why add more non gas products.
I hope you get it running to it's full potential.