Quote:
Originally Posted by synolimit
I pressure tested that small line with the gas cap on, i was wrong. At a few psi the gas cap has a release valve open so its not a direct atmos vent like i thought. The hole i saw under the gas cap just drains onto the tire. So when the tank does build pressure the air can escape. As for a vaccum im gonna guess thats a one way only valve. Not sure how i can test that or if it'll be a problem. I always thought the main issue was pressure and all tanks need a release which i tested and it has. My guy did say we could weld on a new nipple and run another line up by the filler neck for even more pressure release. He said that'd make him feel more comfortable. Again as for the vaccum i dont know. Maybe on the new line run we can install a 2 way valve with a low pressure open/close.
I see what youre saying about the 5/16th hose. I could even Tee it and make like a sideways E for 3 pickups and more volume.
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Sounds like you found a high pressure blow-off in the cap, probably some sort of safety feature, I am not sure I would rely on it as a constant duty device.
The hole that drains by the tire is not a part of the fuel system and can be ignored... this is just to drip out water or fuel that has pooled up outside the gas cap. There is another hole connecting the small port on the rear center of the gas tank to the filler neck tube just inward of the cap. This is a vent that only applies when filling the tank to allow air to escape while fuel pours in. Any time the gas cap is installed, this vent tube is irrelevant.
Sometimes high HP cars will starve fuel when the engine consumes fuel faster than the tank ventilation can alleviate the vacuum. This burdens the fuel pump and will reduce its output. Tank vacuum can create significant problems, so its something you want to make sure to address with priority.
If you add additional legs to the jet pump pick-up, you will defeat the functionality of it any time all the legs are not submerged.