Mine had sat for a long time, it needed a fuel pump. The new one lasted a month or so. I hadn't cleaned the tank well, and it plugged up with accumulated sediment. I ended up putting enough white vinegar to cover the bottom, soaking it for a couple of days. Then I cleaned that out, and added a couple of handfuls of clean sharp gravel, and with a few buddies, shook that around for about 10 minutes. Got the coat of crud out. Someday the tank will probably rust out, but I'll deal with that in 20 years.