Anti siphon valve question

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Jday

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I think my anti siphon valve is beginning to fail. According to what I've read, the aluminum ones, even 3/8 x 3/8, are for motors up to 200hp and brass ones are for motors over 200 hp. My current one is aluminum, the boat originally had a 150hp on it but now has a 200hp. I've used the aluminum with the 200 for two years with no problem, I only just found out there is a difference. I bought an aluminum one before I realized there was a difference. Is there any possible damage I could do to the motor using the aluminum one or should I get a brass one.
 

Antidote

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I haven't heard this before; but, if you haven't done any damage or had any problems in 2 years, I think you're good.
 

warthog5

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They can fail and leave you stranded, cutting off fuel flow to the engine.......Remove it and knock the ball out and reinstall or replace it.
 

Jday

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Antidote, I hadn't heard about it before either, I saw this on the Moeller website.

Wart, I think I'll replace it with a straight thru brass fitting. No check balls to fail.
 

warthog5

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Wart, I think I'll replace it with a straight thru brass fitting.

It's simple to knock the ball and spring out with a small punch and then reinstall.

That what I did to mine.....No running to the hardware store. :
 

knotflying

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I have a stupid question. Where is the anti-siphon located?
 

tomc585

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Its built in to the barbed fuel line fitting on the outlet port/pick up tube of the fuel tank, usually in close proximity of the sending unit
 

Mpellet

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I have a stupid question. Where is the anti-siphon located?
The fitting on the fuel tank that your rubber fuel line meets is the anti siphon valve. The anti siphon valve threads into the pickup tube. You can buy a fitting identical in size and appearance to an anti siphon valve that does not have the ball valve inside. Rumor has it that a lot of folks have replaced their anti siphon valves with these fittings but doing so, I believe is technically against USCG regs.

The image below is what the fitting looks like, this one is brass and does not have the ball valve but would look identical if it did have the ball valve.

These fittings are also made using aluminum.
 

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tomc585

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§ 183.568 Anti-siphon protection.
Each fuel line from the fuel tank to the fuel inlet connection on the carburetor must:

(a) Be above the level of the tank top; or

(b) Have an anti-siphon device or an electrically operated fuel stop valve:

(1) At the tank withdrawal fitting; or

(2) Installed so the line from the fuel tank is above the top of the tank; or

(c) Provided that the fuel tank top is below the level of the carburetor inlet, be metallic fuel lines meeting the construction requirements of § 183.538 or “USCG Type A1” hose, with one or two manual shutoff valves installed as follows:

(1) Directly at the fuel tank connection arranged to be readily accessible for operation from outside of the compartment, and

(2) If the length of fuel line from the tank outlet to the engine inlet is greater than 12 feet, a manual shutoff valve shall be installed at the fuel inlet connection to the engine.
 

cfiorentino

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I would not run a straight tube. If you get a fuel line leak the possibility exists that you could siphon your gas into the bilge without even knowing it. If you are worried about it failing keep an extra on board. They are less that $10.
 

tomc585

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1659963201884.png
Last year when I did my hose changes I inspected mine. Wasn't causing an issue but I'm glad I looked. Cleaned and reinstalled. If there was more room and better access I might have toyed with plumbing in a bypass valve but I think that just complicates things. If I were going offshore often I would make sure I had the tools to remove it if need be.
(remember... everything is more difficult on the water)
 

Bodick93

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§ 183.501 Applicability.
(a) This subpart applies to all boats that have gasoline engines, except outboard engines, for electrical generation, mechanical power, or propulsion.

(b) [Reserved]

[CGD 74-209, 42 FR 5950, Jan. 31, 1977, as amended by CGD 81-092, 48 FR 55736, Dec. 15, 1983; USCG-1999-5832, 64 FR 34716, June 29, 1999]
 

Bodick93

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I don't THINK so. I was of the same opinion you have, and someone on THT pointed this out to me. Note "Fuel Systems" is Subpart J, and applicability (in § 183.501) of this subpart excludes outboards.
 

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Bodick93

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I hear you. My buddy and I both got burned by the A/S valves in our early 2000 and 2005 Sea Pro boats. I have not deleted it yet, but it is on the list. This thread is a good reminder.
 

chas650r

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I also considered removal until I realized IF the fuel line or any thing else fails downstream siphoning lots of fuel is very possible. IF the boat burns from this will the insurance company pay? So I pulled mine out and inspected it which was easier than expected . It was clean and a quality unit, so I reinstalled it . I now know I can get it apart and have the tools and a straight hose barb to replace it with on the boat if needed. Done.
 

Antidote

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ABYC standards require the anti-siphon remain in place In permanently installed fuel systems regardless of inboard or outboard applications.

2414.9.2 Installing an anti-siphon device at the tank withdrawal fitting or along the line, with a rated siphon protection head and flow rate greater than required for the installation.

24.14.11 Fuel distribution and retum lines provided with anti-siphon protection shall be installed in outboard powered boats equipped with permanent tanks, which shall terminate at a fitting at the stem where spillage will not enter the boat.

 
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