Vented gas tank

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edbux

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Two part question. First one...if a vented tank has a non vented gas cap, would it stop the gas flow, sort of like vapor lock? Second, how can I tell if the cap is vented? I was out speeding around..err....driving and it just stalled. No fuel pressure. This happened last year and I changed the fuel pump but haven't driven it that much since then. I'm probably going to yank the tank and get it flushed. That means I'll change the sending unit, which means I'll upgrade it to 3/8, which means running new fuel line, which means I'll add an electric pump. It would be much easier and cheaper if it were the gas cap/venting issue. It used to be the wife never asked about what was in the box dropped off by UPS....lately though....

Thanks
 
I had that problem with a vent line that rusted shut on my Chrysler. Never suspected that until after I had upgraeded/replaced the entire fuel system. After replacing the tank, new electric pump, new pickup, new 3/8 line, still had the problem. Finally dechiphered the one telling clue when I realized after months of dealing with it that the problem was worse with a full tank. Unhooked the vent line up by the engine where it fed beck to the breather one day and tried blowing back through it - nothing - plugged solid. Ran a new vent line, problem solved.
 
wait till it does it again. take off the gas cap. Do you hear air rushing in? You can vent a tank through the cap. I did it on my 72. A couple of strategically drilled holes is all it takes.
 
I don't believe that the 69 & older cars had a vented cap. My 69 Dart has a single vent tube near the filler neck that eventually vents under the car near the tank. Blow some compressed air through that to make sure it's clear.

Something else to consider is the ethenol used in the fuels today. It will literally clean any sludge and varnish from inside the old tank, and this stuff is suspended in the fuel as it flows up front. If the pick up tube is partially clogged, this stuff will easily close off fuel flow. Flushing the tank may not clean out all the old varnish, and the problem will soon return.

I have a 69 340 Dart with the 5/16 pick up and stock pump. I put in a new tank and sender and do not have any fuel starvation problems.

Unless your 360 is really worked, I don't think you need the electric pump and larger pick up and fuel lines. This would save you time and money. New tank & pick up were about $200, and less than 2 hrs to install.

Just my .02
 
My 67 does have the tube coming from the tank to the top of the filler neck. I guess I can disconnect it and blow some air thru it; I should hear gurgling if it's not blocked. If the cap is not vented, where does the venting occur? The FSM states that a blocked vent tube (paraphrasing) can cause the tank to collapse. It appears to me that this is a closed system, I guess we wouldn't want everyone's car seeping gas fumes.

I am leaning towards the sock being gummed up. At minimum I am going to replace the sending unit. May as well go up to 3/8 while I am at it. As for the electric fuel pump, I believe it is just the uncontrollable male thing. Like if a 32" LCD tv is good, then the 54" is what I need.

Thanks for all the info.
 
Vent isn't clogged. Disconnected if and blew air into the tank. I could hear the tank pop like a plastic bottle. I'm going to pull the tank if I can get the filler tube out of the tank.
 
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