What is a Fuel Anti-Syphon Valve?
Boat Manufacturers are required by law to install an anti-syphon valve in the boats fuel system. The valve is usually a hose barb fitting with a checkball and spring inside. It is usually mounted to the fuel tanks pickup tube where the rubber fuel line attaches. Some anti-syphon valves are mounted to the fuel filter assembly on the outlet side. The purpose of the anti-syphon valve is to prevent fuel from syphoning into the boats bilge in the event of a break in the fuel line. The problem is that the checkball inside the valve gets worn and tends to jam thus restricting the flow of fuel. The symptoms of a bad anti-syphon valve are, hard starting, surging RPM’s while under way, hesitation or backfiring upon acceleration and lack of wide open throttle (WOT) RPM’s. The solution is to replace the faulty anti-syphon valve. That said, many customers elect to just knock out the ball and spring or replace the valve fitting with a standard hose barb. This can improve performance and is less trou
