Anti-siphon valve...friend or foe?

[Halfhitch]

I had an anti-siphon valve stick closed on a previous boat so I replaced it with a regular barbed fitting. The day it happened I was taking some family members for a look-see cruise out of Olympia, Washington in Puget Sound. After launching the boat and starting the engine while tied to the dock, I left everyone there and went to park the truck. When I came back the engine was off. I asked why they had turned off the engine and they said.. "it just died". It was a 4 year old Yamaha F150 and it never died before that. I tried restarting and no luck. It took me the best part of an hour at the dock to figure it out and get it going. Needless to say the enthusiasm for the trip had waned but we were off. Me smelling like gasoline and the women cold and shivery from standing around. We all know that's not good. I never put that ASV back in and the engine never stumbled again.

Now here I am with a new to me 2004 Grady. My first Grady, and yes, now I see there is "a difference". The boat is in exceptional condition and when checking out the aluminum tank...."lo' and behold"... the enemy!...an ASV. I see that it is constucted of different material. The one that caused me grief was made of aluminum. This one appears to be brass or bronze. I haven't scratched through the patina to see.

I am wondering if the Grady owners have experienced a downside to the ASV installed in their boats. Have you ever had trouble with it? Have you removed it altogether? Have you replaced a bad one with a new one? Whats your opinion of the necessity of haveing one? I would like to hear any views/opinions for or against these little wonders.

 

[DennisG01]

The ASV is DEFINITELY your friend. DO NOT remove it. This is used on ALL boats, not just Grady's. It's sole purpose is to keep your bilge from filling up with fuel if a hose should spring a leak. Bad things can happen, both to you/family and the environment, if the valve is removed. If you want, just remove it and clean it out every few years with Brakleen. I believe it's also a CG requirement - so IF there should ever be an insurance claim centering around fuel leakage and the ASV was removed... good luck getting a payment.

 

[Another Distraction]

More important with inboards.

 

[SkunkBoat]

I personally know two people who had problems with them (at a bad time).
I have heard many times on other forums to remove them because they are a problem waiting to happen.

I did not have one on my last boat. When I replaced the fuel tank, the tank shop did not put one on, they put on a new straight thru barbed fitting.
I researched it 10 years ago and seem to remember that the requirement was for inboard motors and where the tank is higher than the motor (or the fuel line dips below the tank height).
My line went up to a filter.
I put on a fuel shut off valve instead.That way, if I had to remove the fuel line in an emergency or had a leak in a line, I could shut it off at the tank.

I have not checked my new-to-me Grady tanks for them yet. Tanks were replaced by PO last year.

 

[Halfhitch]

That's what I have understood is that their function is to prevent fuel from getting into the bilge due to the siphon effect but if the fuel line and engine are above the top of the tank they are not required and really have no use. The thought that they are to prevent drain-back from the engine I believe is in error. The first line of defense for that occurrence would be the fuel line bulb it would seem to me.

I will probably leave the ASV on my tank but carry a straight through barb fitting in my kit, should it ever act up.

 

[Harpoon]

All boats do not have them. Remove it if you have an outboard.

 

[DennisG01]

I looked up the CG requirement and, Skunk, you are correct from what you researched years ago. As long as the fuel line stays completely above the tank the ENTIRE time to the engine (whether OB or sterndrive) - no dips, or possible dips - then it is not required. But, you'd have to physically check the fuel line along it's entire path. Simply "removing it because the boat has an OB" would not be good advice. The law has nothing to do with OB or Inboard - it seems entirely dependent only on tank height vs fuel line height.

For what it's worth, I've worked in the marine business for 30 years and I can probably count on one hand the amount of times that a failed AS valve has come up. Sure, it happens, but it is pretty rare. But maybe that's also because the places I have worked at are inland and subsequently get better fuel quality (on-road gas stations) on average? We have also been big on recommending fuel additives and I think it's very reasonable to assume that since the additives help to prevent fuel from gumming up, the additives help keep the AS from clogging up, too. They are VERY simple thing - a spring and ball. If the fuel passing through it is clean, it's nearly impossible for it to fail.

 

[Harpoon]

Lol, I have a buddy that had an old Grady and the anti siphon problem was intermittent- drove him crazy, rebuilt carb, changed filters, coils, wires etc. then by the end of his season he found the anti siphon.

I had one with the problem in the past too... but I figured it out by running on aux tank.