A couple of years ago, a boat was lost when returning from Bermuda, as least partly because gunk in the fuel stopped the engine, and I know of at least two boats that lost their engines on the way south last fall for the same reason.
This is a particularly insidious problem because gunk can lurk at the bottom of the tank for years while a boat is only being sailed inshore, but will bring the engine to a shuddering halt after only a few days of offshore motion stirs things up.
The best solution is to open the tank prior to going to sea, and manually clean it—a filthy job, but well worth while before a first offshore passage.
A second, although not as thorough option is to hire a fuel polishing company.
But once we have the tank clean how do we keep it that way?