fuel fill cap is the only venting component on modern day fuel tanks

Be that a vented cap or a hose running to a charcoal canister like a lot of ot cars have or vent hose running up high enough and in a spot it won't burp gas or gas fumes inside the car. Probably the easiest fix is drill the cap so it vents all the time or get an old original cap that vents.Īt any rate the tank has to have some sort of venting system in place.

The second time I had a can of gas in the trunk and when I opened the cap I heard the sides of the tank pop back out. The first time I walked a mile to a gas station and got gas and walked back, put the gas in the car and fired it right up. I went through three new off the shelf Stant brand 'vented' caps before I got one that worked on my 51 Merc 30 years ago. the cap doesn't vent and pressure builds up in the tank. The fuel level of your tank changes throughout the day, even if you are not driving it.

Gasoline expands in volume as it warms up and shrinks in volume as it cools down. In order to breathe, your tank must have a vent somewhere that will relieve both vacuum and pressure. Just the opposite happens when the rig sits in the hot sun. Fuel Tank Venting Your tank has to breathe. It has to vent both ways and what is happening is that when the fuel pump pulls gas from the tank there is no air going in thought the vented cap to replace the gas. I see a lot of bs up above but the real problem is that your 'vented' cap is not venting.

Fuel fill cap is the only venting component on modern day fuel tanks