5. My fuel tank is higher than my engine. Do I need an anti-siphon valve? There is a small round valve installed just above the tank where the fuel line leaves the tank. Could this be some sort of anti-siphon valve?

The valve to which you are referring is probably a small spring-loaded one-way check valve. The spring-loading on the valve is sufficient to prevent fuel from passing through it statically through a siphon (usually no more than 2 or 3 psi), but low enough so that the fuel pump can pull fuel through its mechanism while the engine is running.

These check valves will sometimes create a problem with electric pumps, since they (electric pumps) are less forgiving of even slight increases in suction head than are mechanical pumps.

If there is a wire connected to the valve on your boat, it is probably an electric solenoid valve that spring-loads closed whenever the ignition switch is turned off, and power is removed from the valve. These valves have the advantage of adding virtually no head loss to the suction side of the fuel pump, but they are vulnerable to malfunction, since they rely on electrical energy to hold them open.

It is not at all clear to us that either of these valves is actually required by the Coast Guard. In our experience, most people rely on a manual valve to prevent fuel from passing from their fuel tanks when the boat is left unattended. - Updated: January 5, 2004