Small hole in fuel filler tube (1 Viewer)

middlecalf

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Pay attention to what @Mark Jennings is saying. Vented gas caps are for letting air in to avoid vacuum. They are sealed for air (or fuel, like in a roll over) trying to get out. That’s what the weep hole is for, to keep pressure from building in the tank and then possibly rupturing something not intended to be ruptured. Also, as pressure goes up in a fixed volume the temperature must rise, generally not desirable with fuel. The weep hole is not a bad design, in fact a good simple and functional design. When the environmentalists forced the emissions controls the designs went from simple and effective to complex and less effective (or rather higher maintenance required). So don’t overfill your fuel tanks, simple.
 

Living in the Past

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Here is where the chain hooked on the 62 neck.
IMG_20201023_122703963.jpg

Here is where the chain hooked on the 69 fill neck. Hole for the chain is larger. Also only used three bolts to mount to the tub verses four.
IMG_20201023_122606216.jpg

Thia is the neck off a 61 FJ40. Can see where the chain attached and small weep hole to the right.
IMG_20201023_122857824.jpg

The FJ25 FST the fill neck was part of the tank. The chain attached to extension for the fill neck. Take off the cap and pull the extension and can pour directly out of a jerry can into the tank. Probably messy doing it that way but made it a lot easier to get fuel into the tank if you didn't have a funnel or spout to use. The complete tool kit, hand crank to start the engine, hand primmer on the fuel pump and the fill extension these were build to get you home for almost any emergency.
 
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This is correct on OLDER (all I have had/worked on. Vent hole as shown on ALL of mine, and the chain hole is inside on the "catch" lip. On side hill and full tank it would pee.....
 
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So if one wanted to cover this ill designed "vent" (now that we know this is not a great design), what is a vented cap that will fit on our old rigs?
I disagree, was not an ill design, was the standard for ALL auto manufacturers.....back when the expectation was people would be responsible owners...not overfill the gas tank...drive within the vehicles capabilities....be smart and proactive with maintenance. Anymore, we have to be protected from ourselves......and the lawyers.

Go ahead and fill the hole if you think it’s really really bad. And when your truck won’t start because you drew 30” of negative pressure or you pressurize the tank to the point it blows the filler connecting hose and you’re truck burns down......
 

red66toy

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I disagree, was not an ill design, was the standard for ALL auto manufacturers.....back when the expectation was people would be responsible owners...not overfill the gas tank...drive within the vehicles capabilities....be smart and proactive with maintenance. Anymore, we have to be protected from ourselves......and the lawyers.

Go ahead and fill the hole if you think it’s really really bad. And when your truck won’t start because you drew 30” of negative pressure or you pressurize the tank to the point it blows the filler connecting hose and you’re truck burns down......
I did say fill the hole in conjunction with a appropriately vented cap... :p I in no way stated that it would be a good idea to completely seal the fuel system. But thank you for the epic scenario!
 

FJ40Jim

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1962 cap. Venthole connects to tiny notch on outer lip. When cap is installed correctly (stylized T oriented correctly) venthole is at top of cap.
There is also a 1mm venthole in bottom of neck, not visible in pic.
DSC00578.JPG
 
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Interesting. I assume the stock cap at the time was not vented- why have both holes.
Anybody think putting the hole at the top of the pipe would be dumb? Can’t imagine it would be that much more susceptible to water getting in (plus mine is always garaged). That way less likely to drip out. Good news is Hagerty insurance cut me a check really quickly and my paint maestro is working on it now.
 

Rainman

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I'll pitch in too. BUT!

Why in the hell isn't the weep hole simply a pressure relief hole on the UPPER side of the tube? That way, gas wouldn't "pee out" on steep grades or if you're filling with a gas can and the neck doesn't go far enough in. Just looks like a serious goof in location to me.
 
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