Anti Siphon problem?

[Hdog412]

Hi everyone,

I hope everyone's weekend is going well.

I have a problem getting fuel of the boats fuel tank, and I am thinking that it the anti siphon valve. I know it's a stupid question, but I would rather ask a stupid question than make a stupid mistake and I have been working on this thing for the past 4 hours. The ball get sucked flat when i pump it. I hooked up a 6 gallon fuel tank from another boat and it ran fine. I have a 16 foot key Largo with a 50 HP Johnson.

If anyone has any ideas let me know. Also if I take off the fuel line going to the motor from the tank is that where the anti siphon valve is? If anyone had an image that would be great.

In any case thanks in advance i have always benefited from great advice from these forums.

Best Regards

Harry

 

[BaileysBoat]

Re: Anti Siphon problem?

Welcome Hdog.
You have solved your problem. The valve is actually a drain back valve to
keep the fuel in the engine draining back into the tank. Might be a plugged sock filter in the tank

 

[ondarvr]

Re: Anti Siphon problem?

The anti siphon valve is normally right at the tank connection and they do get stuck. It can also be the squeeze bulb, they tend to go bad in a few different ways.

The anti siphon valve stops fuel from being siphoned out of the tank into the hull if a hose or fitting starts leaking.

 

[emdsapmgr]

Re: Anti Siphon problem?

I'd unscrew the anti-siphon valve from the tank fitting (which as already mentioned) and check the chrome ball (valve) for movement. It is common for debris from the tank to get sucked up into the ball valve chamber and restrict the movement of the ball. It should have light pressure from the spring, but move easily one way. I'd blow it out with carb cleaner to make sure the movement is free and easy. If that does not fix your problem-look to the tank hose. It is also not unusual for the ball valves in the fuel hose squeeze bulb to cause problems and restrict fuel flow. You can replace the hose bulb only-but a whole new hose is not that expensive. Some recommend that the squeeze bulb arrow be oriented upward during normal operations.

 

[ezeke]

Re: Anti Siphon problem?

Don't exclude the screen on the fuel pick-up inside the tank; at least on this forum it has turned out to be a more common problem than the anti-siphon valve.

If you have a full sized water separating fuel filter between the tank and the primer bulb, the screen is less important.

The function of the anti-siphon valve has nothing to do with preventing fuel from flowing back into the tank.

If all of the fuel system is above the level of the top of the tank, the anti-siphon valve is not required.

Also, be sure to check the screen on the tank's vent at the hull, they sometimes become clogged.

 

[Chris1956]

Re: Anti Siphon problem?

My '88 SeaRay had a stainless mesh filter and A-S valve in the fuel pickup tube. The fuel pickup tube needed to be unscrewed from the elbow to gain access.

 

[Hdog412]

Re: Anti Siphon problem?

Hello again,

First thanks for everyone's replies.

So, yesterday I planned on taking advantage of the extra light and removing the the anti siphon valve which I was having difficulty removing, unfortunately while removing it I broke it off and never got the threads from the valve out, looks like a cheap piece of aluminum. Any good ideas of removing the remaining piece of the A/S valve from the fitting? I was thinking of using a cordless drill and slightly bigger than the hole drill bit to see if I could break it apart, but I am afraid of igniting a fire since it is so close the tank (that is why I am going cordless and not using a more powerful drill).

One positive thing is that it looks like it is the valve because the part I was able to get out had a lot of "sand like" debris

Thanks again

Regards

Harry

 

[Chris1956]

Re: Anti Siphon problem?

A drill has many open sparks. Do not use it to driil the tank, or it will start a fire or explode.

Drain the gas out of the tank, and fill it with water to the top, in a well ventilated place. Now it will be safe to use the drill, as the water will push out the gas fumes. Use an easy out to remove the remains of the A-S valve.

 

[ezeke]

Re: Anti Siphon problem?

Almost all prefabricated tanks have a pickup that can be removed by unscrewing the flange at the top of the tank. You need to inspect the screen anyway, so why not remove the pickup, inspect the pickup screen, remove the broken fitting, and then put it all back.

 

[Hdog412]

Re: Anti Siphon problem?

thanks for the tips, I was really unsure about the drill and hesitant to use it for fear of the fire issue, I just didn't want to have to take off the center console to take out the tank, but some times you gotta just bite the bullet.

I really appreciate your help

Regards

Harry

 

[emdsapmgr]

Re: Anti Siphon problem?

Most marine dealerships sell replacement industry standard fuel pickups. Unscrew your old one out of the tank and throw it away. Get a new one and cut the nylon pickup hose to length and screw it back into your tank. It's a cheap/easy fix.