03
Jul
Your tank has to breathe. Regular maintenance of a charcoal canister ensures that a gas tank is vented properly.
If there was no way to fill that vacuum it might overcome the pressure of the fuel pump and your motor would starve for want of gas.
Best way to vent a gas tank. The filter traps the fumes and sends them back to the engine through a vacuum hose to be thoroughly burned before being released into the air. Regular maintenance of a charcoal canister ensures that a gas tank is vented properly. Your tank has to breathe.
In order to breathe your tank must have a vent somewhere that will relieve both vacuum and pressure. Gasoline expands in volume as it warms up and shrinks in volume as it cools down. The fuel level of your tank changes throughout the day even if.
Rollover valve should be installed at tank vent line should be 14 and have atleast two large 3 loops in it the loops helps prevent the vapors from coming out as they are heavy and settle in the bottom of it. You can install a electric valve in the vapor line that opens when the ignition is keyed on did this for one car its a tank switching valve from a chevy 78 k 20 truck. 8 May 2 2011.
The cap should vent to atmosphere not sure if the first gen cars do or not. If not you have created a sealed system and the pump will create a vacuum in your tank because there is no way for air to replace the pumped fuel. I guess the best way to vent the tank would be the stock setup however the tpi 350 would have a supply and return line from the tank Im assuming so look into self venting fuel caps or run a line from the tank to the charcoal canister with a roll over valve between and from there go to the air cleaner.
Ive seen simple setups where they go. If your installing a tank on your 34 chev than normally it would be under the trunk floor and a simple vent to air would vent it. If your going to install a Moon tank IN the trunk then it would have to be vented to the outside and a simple 14 in plastic hose from top of tank through the floor should do.
1 The fuel tank vents to open space. 2 Electrical components are ignition protected. 4 No connecting compartment that requires ventilation.
5 Metallic or non-metallic tank meeting certain permiability requirements. But as soon as the vessel carries 7 or more passengers tank space vessel ventilation is required. Yes you do.
I just went through this with the install of a FiTech EFI. I originally used my vent to tank as return. It worked fine except when Id dump gas in it would blow back filler and make a mess on me and rig.
I ended up installing a T fitting on my fuel pump inlet and running return to that. Seems to be the ticket. Hot Water Heaters.
How to Properly Vent a Gas Water Heater - YouTube. One other option is to use welding gases. If you have access to MIG or TIG welding gases you could fill the tank with an intert gas mixture such as CO2 75CO225Argon or pure Argon.
The Argon is heavier than air and would stay in the tank preventing combustion should a spark be generated. A water heater using atmospheric venting or direct venting will allow the fumes to exhaust naturally by rising straight up through a vertical vent which is routed to the homes chimney or through an upward sloping vent which may be routed through the chimney or through a wall to the homes exterior. What I would have done baring drilling a hole in the top somewhere is to drill a hole in the bottom and use a brass tube up into the neck area where it would be at the highest point and vent that to ground.
On the same order as the overflow pipe on a radiator. If youre running a stock tank and have determined that you need better venting install a small fitting into the top of the filler neck somewhere where gas wont enter it when you fill up and run a hose to the outside through the trunk floor or something. Keep the outlet away from the exhaust.
I have a stock tank with a sump welded in the bottom Draw is from the sump of course return is threw the stock draw enlarged to 12 vent is the stock return. I ran a line up to a rollover check valve through the floor of the trunk and ran a hose back down from the check valve through the trunk back down above the axle as to keep the vent outside the trunk. Well if youre venting I would definitely add the gaskets first thing to snug it up.
Then you need to seal the old venting as was already said JB Weld will do it then just drill from the top center big enough to fit some fuel line. Dave I have been making a charcoal cannister for years for streetrods never have I smelled gas in my garage and have done multiple cars very simple also after your rollover valve run the line from the valve up higher than the gas tank and make a loop either out of hose or tubing from there I pass it through a bulkhead to the outside of the car and I make a small 2. The gas tank vent is a one way valve.
It relieves pressure in the tank. If you suck on the hose what. You will notice the valve release.
If you blow in the vent hose it builds pressure in the line not in the tank. I know its sounds like a lot of sucking and blowing on a hose but were not on the mavrick fourm. I normally loop the vent line up and back down that way if the plane is inverted then it doesnt dribble out on you.
Some guys like to run two or three loops around the fuel tank for the vent too. The idea is to loop the fuel line up and over and back down so that when the plane is inverted the fuel doesnt dribble on on you. All outboard motors have vented gas tanks.
As the fuel pump sucks fuel out of the tank the fuels departure creates a small vacuum inside the tank. If there was no way to fill that vacuum it might overcome the pressure of the fuel pump and your motor would starve for want of gas. Some outboard gas tanks have a vent that opens as pressure.
If you think tank pressure is causing problems put a fuel pressure gage at the carb to see how high the fuel pressure is. Not sure how the fuel would come out the bowl vent tubes as they are rather larg could it be the accelerator squiters if so heat from the manifold can cause them to squirt and if this is the case you may need a heat sheild. GM used a two way vent valve that lets air in but allows the tank to pressurize up to about 8 or 10 psi then releases any pressure and fuel vapor above that to the atmosphere.
Works great but this is in an EFI fuel system with a common steel gas tank. Dont know if it would apply to a plastic fuel cell with a carb.