A friend of mine wants his boat run more often so he is keeping at my house. He just got a 12 gallon ventless tank and brought it over full two weeks ago. I just went out to fire up the boat and found an empty tank. All 12 gallons slowly went through the water separator up the fuel line, through the strainer, out the carbs and down the motor. At least that’s how I figure it. The inside of the cowling is flooded with gas. Literally the whole fuel tank has been watering my grass. It happened over a period of two weeks and I have been too busy to notice until now.
What gives? I have never had a “ventless” tank. Do I need to tell him to store it with the cap open?
It is a portable. I called him, and he said there was an instruction manual with it but he lost it. The cap says, tighten until it clicks. If you do that, it blows up like a balloon.
I know all mounted tanks are required to have an anti-siphon valve. I’m not sure but the siphon effect could be your problem. Maybe you could splice a valve into the fuel line? 12 gallons of gas is about $40.00. Too much to let drain out onto the driveway.
10-4. There is no quick disconnect on the fuel line at the tank or the motor. If there was, I would disconnect it. I like the idea of installing a shutoff valve. I will search online for the manual. Thanks for the replies.
If it’s new then the cap should have a two way vent valve. I know some of the early model caps were faulty. If it’s expanding like it’s about to pop then the valve in the cap may be screwed all the way down or not working at all. The new two way vent valve caps should work both way releasing pressure, vacuum and expansion.
Read an article on the new tanks a while back. IIRC, the new tanks are NOT meant to be vented. That’s the whole idea - to prevent releasing nasty dangerous noxious baby-killing gasoline vapors into the air. The fuel hose (from tank to motor) that is intended to be used with these new tanks is supposed to have a fixed pressure valve that prevents excessive pressure from making it to the motor.
It is ENTIRELY possible to have one of these tanks develop enough pressure, even when the motor is running, to push gas through the carbs and flood the motor. This pressure can accelerate wear on internal carb parts.
If you have one of these new vent-less tanks, you need one of the new pressure regulated hoses.
EDIT - I did not make it clear that I think this stuff is a bunch of nonsense. I completely agree with all who have said crack the cap and don’t store with line connected to motor.
So basically the hose is venting the tank in lieu of the tank cap. I don’t see how that is any better than the cap doing it…UNLESS of course your portable tank is in an enclosed compartment.
I do not have the hose & my tank is not in a closed compartment so I just back off the cap a little & problem solved…
My cap does have a little screw like plug on top of it that is not for venting but is for if the tank builds up too much pressure it will blow off that part & not blow the lid off or mess the tank up. Although I do not trust it because I have seen my tank swell up to the point to where it looked like it would pop if you touched it so that is why I started loosing the cap.
I always unhook my hose from teh motor when I am trailering the boat or it is in the yard. I had too much pressure build up one time trailering it with the hose on & it blew out a gasket on teh motor. Mechanic told me to alsways unhook it so that would not happen.
Remove the cap, turn it over and force the little ball check through with a small punch. Problem solved. Otherwise, they blow up like a balloon in the sun if the cap is tightened, then the pressure can force fuel through the carbs if not disconnected.