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71 challenger fuel tank venting

Flchallenger

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My 4 tank lines are blocked off now and have a vented cap but still getting vacuum build up in the tank. Just put a rebuilt 500 ci stroker in with a 850 quick fuel. Which seems to suck a lot of gas thru that 3/8's inch line. I have the 71 style sending unit with no venting. So I am thinking of running a rubber hose to one of the 4 vent tubes on the tank to the top of the wheel well with a fuel line check valve and a fuel filter for filtering air. Also I don't know about other years but tank cap has a rubber seal to keep water out would also act a barrier for air flow regardless of a vented cap that is not venting enough. What are your thoughts. Also which of the 4 tubes should I use?
 

Adam

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Perhaps you could just add a small check valve to the top of the filler neck inside the trunk; somewhere out of view. Something that would allow air in, but not vapors or liquid out. The four gas tank tubes go to the corners of the tank and were essentially the same in venting capacity. Those tubes were then connected to four different length tubes, inside a vertical riser inside the trunk, near the fill tube. Or you could alway go back to stock.
 

Flchallenger

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This is what I came up with. A one way check valve and a filter. Also I used a 1/2 inch pex fitting on the hose so there is no clamp with screw. Nice and clean look

20201017_142012.jpg
 

moparmarks

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On the 4 lines they each go to a corner of the tank. One goes to one corner and another one goes to another corner and so on. On a 71 the 4 lines went to a vapor tank in the trunk. On 72-74 they go to a smaller vapor tank mounted on the shock cross member. The vapor tank then has a 5th line that ended up at the carb where the vapors consumed with the fuel mixture.
Just connecting a hose to one of lines might result in fuel spilling out of it. I'd find a vapor tank and go that route.
 
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