fuel tank/anti siphon valve

spete

Petty Officer 2nd Class
Joined
Jan 27, 2003
Messages
168
read some postings re: sticking anti-siphon valves on fuel tanks causing rough running motor at low rmp's ...<br /><br />Do all fuel tanks have anti-siphon valves?<br /><br />Where do I locate the valve?<br /><br />is removal acceptable/are there any hazards associated with removal?<br /><br />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.
 

rickdb1boat

Supreme Mariner
Joined
Jan 23, 2002
Messages
11,195
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.
 

acc

Seaman
Joined
Apr 9, 2003
Messages
59
Re: fuel tank/anti siphon valve

I second Admiral Rick's suggestion.....having been there... done that.....<br /><br />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
 

spete

Petty Officer 2nd Class
Joined
Jan 27, 2003
Messages
168
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
 

rickdb1boat

Supreme Mariner
Joined
Jan 23, 2002
Messages
11,195
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.
 

spete

Petty Officer 2nd Class
Joined
Jan 27, 2003
Messages
168
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- <br /><br />checking this evening - puddle fuel check valves/tubing/Pulser coil/ignition coils/rule out or confirm CDI unit malfunction
 

cparker072

Seaman
Joined
Oct 2, 2009
Messages
56
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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