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  1. #1
    Petty Officer 2nd Class
    Join Date
    Jan 2003
    Posts
    168

    Default fuel tank/anti siphon valve

    read some postings re: sticking anti-siphon valves on fuel tanks causing rough running motor at low rmp's ...Do all fuel tanks have anti-siphon valves?Where do I locate the valve?is removal acceptable/are there any hazards associated with removal?The fuel tank fill/gas cap fitting on my center console boat is in a recessed black box with a fill cap and a vent. (brand name is Attwood) Looking inside the console I can see the vent hose and the large fuel hose heading towards the tank. I checked the vent and it looks clear. I don't see anything that appears to be an anti syphon valve - just a the black hose material on both the vent and main fuel filling line. Is the valve inside the hose itself? Wanted to check or remove to help eliminate a rough idle I'm having.

  2. #2
    Supreme Mariner rickdb1boat's Avatar
    Join Date
    Jan 2002
    Location
    St. Louis, Mo
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    11,183

    Default Re: fuel tank/anti siphon valve

    the valve is located in the fuel tank fitting. If I might suggest it, why not get a different portable 6 Gallon tank and try that first to eliminate the fuel tank as the cause of your problems. Only $20.00 or so at Walmart.
    Rick

    "Boating is Life...All the rest is just Details"

    2007 Bentley 200 Cruise
    2007 Merc. 90 4 stroke

  3. #3
    Seaman
    Join Date
    Apr 2003
    Location
    Destin FL
    Posts
    59

    Default Re: fuel tank/anti siphon valve

    I second Admiral Rick's suggestion.....having been there... done that.....Location of the valve....On my boat it was located at an 'L' shaped brass fitting in the fuel line first coming out of the tank.....it screws into the 'L' shaped brass fitting and the fuel line hose connects to it

  4. #4
    Petty Officer 2nd Class
    Join Date
    Jan 2003
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    168

    Default Re: fuel tank/anti siphon valve

    Good idea on the portable tank - hose is hard wired so to speak into the motor - i guess i can detach/attach at the fuel bulb. The more i think about this - wouldn't a bad valve give a constant starving fuel problem? Mine is more intermittent and rough idle usuall after getting warmed up. Trying to eliminate all simplest things first. Thanks for the info

  5. #5
    Supreme Mariner rickdb1boat's Avatar
    Join Date
    Jan 2002
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    St. Louis, Mo
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    11,183

    Default Re: fuel tank/anti siphon valve

    If it runs good at all other times, save your money and forget the anti-siphon valve. Post a new topic on your problem. Could just be spark plugs or carb adjustment causing the rough running.
    Rick

    "Boating is Life...All the rest is just Details"

    2007 Bentley 200 Cruise
    2007 Merc. 90 4 stroke

  6. #6
    Petty Officer 2nd Class
    Join Date
    Jan 2003
    Posts
    168

    Default Re: fuel tank/anti siphon valve

    Thanks Rick - will rule that one out. So far I've replaced plugs, sync n link, decarbed, fresh fuel, checked coil grounds, don't see any obvious visible gasket leaks/fuel leaking/bad fuel line connectons/etc- checking this evening - puddle fuel check valves/tubing/Pulser coil/ignition coils/rule out or confirm CDI unit malfunction

  7. #7
    Seaman
    Join Date
    Oct 2009
    Location
    Stuart, FL
    Posts
    56

    Default Re: fuel tank/anti siphon valve

    have a fuel leak in my 86 70 hp evinrude it runs fine no problems with idle or anything but when boat is parked on trailer it leaks gas/oil could this just be the anti siphon valve or something else? please help the dolphin bite is hot and im docked!

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