I’m working on getting one of my 1973-1974 Mercury Capris (V6, 2.6 and 2.8 liters) running again. They’ve been sitting for years. One’s an organ donor, the other is more likely to be resurrect-able. I’ve been told that if cars sit that long, I’m going to have to flush out all the varnish or whatever in the fuel system. Sea Foam has been recommended (not sure which product) to attack the fouling. Today for practice I took the (in-trunk) gas tank out of the worse of the two cars. Still holding about 3 gallons of really foul-smelling, yellow gas from… 15 years ago??? No external rust, no leaks — it’s in a dry, protected place in the trunk behind the rear seats. There was some sediment, like rust or maybe little bits of tar; and a tarlike substance on the in-tank fuel strainer on the pickup, and the pickup tube was clogged. Lacquer thinner dissolved the gunk on the strainer. Mineral spirits didn’t touch it. Poked welding rod through the pickup tube and scrubbed it as best I could with pipe cleaner and a parts washer.
I cleaned those up, but I suspect that’s just the tip of the gunky iceberg. How do you recommend proceeding? I figured send the tank out to be boiled. But, what about the lines from the tank to the pump? And, probably less critical, pump to carb? Will your products do anything to clear out the lines?