Anti-siphon needed?

[Steplift 72']

Originally Posted by cterrebonne

US coast guard requires boat builders to install an AS vavle or an accesable valve that can be closed comming off the pick up in case of fire/fuel hose leak. i run a straight barb. but if you still want to be able to close off your fuel supply you can install a valve that screws into the fuel pick up. if the straight barb doesnt fix it, you might want to pull your fuel pick up out the tank.

I've ran into trouble with an anti-siphon valve where the motor would intermittently lose rpm and would shut down if the throttle wasn't pulled back. The motor was vapor locking apparently because the AS valve spring was too stiff. I believe this problem is more common during months where "winter gas" formulation is used by the refiners, especially in spring when the weather begins to warm up a little. That can be really dangerous to the powerhead to lean out at cruise speed.