Check Valve at gas tank?

[DaveK]

I've had a problem with the engine this weekend and traced it to the check valve. I've also done quite a bit reading here today and found what Don has to say about these here.

8) Lastly, spring-loaded check valves used as anti-siphon devices sometimes cause or at least exacerbate problems. These valves are usually installed where the pickup tube leaves the top of the tank and function by adding more head loss (approximately 2 psi) than the weight of the fuel in the line downstream of the tank. In this way, if you leave your manual shut-off valve open while leaving the boat unattended and a major leak develops, fuel will not flow from the tank. These valves are OK in principle, but the "controlled restriction" that they introduce, does have the potential of creating problems in some fuel systems. For example, I think they would be really troublesome in the Catalina 30 fleet, with fuel tanks so low and far from the engine.

The question is do I simply leave it out of the system and shut the fuel off when I leave the boat? Or, should I use a smaller check valve that doesn't have so much resistance in flowing fuel the right way?

Thanks for the site and the info here!!!
DaveK

[Don Moyer]

Dave,

I can only report that I removed the check valve from our own boat and rely on the manual shut off valve. I know of no Coast Guard requirement for a spring-loaded anti-siphon valve. I don't know how much luck you'll have finding a spring-loaded check valve with less than a couple psi back pressure, and if you did, it would largely defeat the purpose of the valve.

Don