Generally when folks are talking about the anti-siphon valve, they are referring to the one built in to the priming bulb. I would not add a second one: serves no purpose to have two in a row and they are definitely a failure point.

Those symptoms sound like water in the fuel: does your boat have a spin-on fuel filter/water separator? They are frequently not installed by dealers and most folks (including me) would tell you they are an absolute necessity. If you left your boat stored all winter without a full tank, or it is stored outside, it is quite common to get water in the fuel. A high quality water separator is a life saver.

 

Positize - appreciate the info. I was leaning toward the siphon as the cause because I've replaced the fuel pump which was shot and that helped a lot & stopped the rainbow of fuel all over the water. But still have had issues starting consistently and when it died on middle of the lake the other day I had Melissa check the bulb while I turned the engine over and where it had been full a few minutes prior it suddenly was flat and empty. She gave it a few squeezes, once it filled up I turned the key and it fired up. But maybe it is more the valves on the bulb pump are wearing out. It is a 2005 boat/motor and most everything looks original.

I don't have a fuel filter/water separator on it but that's on my to-add list. I bought this used in Feb so not sure how the previous owner cared for it. Definitely was and still is stored outside.


-shane

 

As soon as you start having symptoms like this, replace (or, in your case, add) the fuel/water separator. I replace mine at the beginning of every season (and prefill the spin-on filter with pure Seafoam).

Then replace the entire fuel hose/priming bulb assembly if that does not help. I can guarantee you it is well beyond time for replacement if that is the original hose assembly. Did you see the thread recently where the OP showed the inside of his fuel hose assembly (full of shards of failed hose)? The alcohol in our fuel chews up the inside of the hoses.

One other thing you'll learn: buy the original equipment Yamaha, Honda, Suzuki fuel hose assembly. The aftermarket ones are junk. This is one of those cases where you absolutely don't want to save a buck.

 

Replacing fuel lines is a great point to make. The Coast Guard recommends replacing all of them (including fill tube and vent lines) them every 10 year at a maximum. Be sure to get Cost Guard approved fuel lines marked A1-15 which also meets the EPA regulations.

 

The anti siphon valves you speak of are for below deck fuel tanks and threads on to the pick up tube on the tank. If a fuel line coming off the tank were to fail or come loose and it lays below the tank it'll stop gas from running (siphoning) into your bilge. above deck tanks wont have them normally,,,gregg

 

I didn't see this noted in any of the other replies: The anti-siphon valves the OP is talking about were only required for inboard engine boats with permanent fuel tanks.

That being said, they are often installed aftermarket in a situation where a second engine is added and will be drawing fuel from the same pickup as the main engine.

Also worth noting is that they do corrode and fail from time to time. Symptoms are similar to a failing fuel pump........... and in some cases causes a fuel pump to fail as the pump cavitates or overheats.

 

Thanks for all the info on anti-siphon valves and advice on my problem. I am also replacing fuel lines/ball bump and will let you all know how it goes once I get it down to the ramp for a test this weekend.

Shane


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