Fuel Tank Overflow ?

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Marv1

Marv1

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I just got my 74 Dart Sport and filled up today. I may have overfilled tank. I heard gas coming out underneath car. I looked under and noticed gas coming out a short horizontal tube at top of tank. Is this some type of overflow tube. Seems to be stopping, but was coming out pretty good at first. Is this normal ? Thanks
 
That's odd, can you be more specific on where the tube is? I have a 74 DS and there is no tube vent on mine, although there IS a second tube coming out at the sender for a return line.
 
Looks like it's right at top of tank, small rubber tube horizontal
 
imagejpg3.jpg


Hope this helps
 
It was half full when I started , but I believe I overfilled but ran out this tube,,
 

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looks like that should go to the charcoal canister. Just cap it if you dont have a canister. Dont want it open as itll draw moisture into the tank, stink up the car and be a fire hazard....
 
You cannot just cap it, it IS your vent. If the carbon "up front" stuff is gone, you need to "do something" with it.

There are a couple of ways. One is to duplicate the earlier 69 and back stuff..........

which is pretty simple. A tube up high in the filler neck, going up as far as possible against the top of the inside quarter fender, then back down through the trunk gasket

http://i55.tinypic.com/2cmugso.jpg

Another might be IF that left over line is coming from the vapor separator, would be to extend it up over and back down.

Some guys want to suggest venting the cap, but this can result in fuel all over the rear fender.
 
Mmmmm. looping the tank vent line on to back to the upper filler neck closes off the vent.....but the tank need to be vented (like with a vented cap for instance) somehow or the pump will suck a vacuum on the tank and partially collapse the tank. BTW I recall that the above vent back to the upper neck was there for anti-surge of fuel back up the filler when filling the tank; it is not the vent for the tank. The line would also help return any fuel to the tank that did surge up the filler while driving.

The open line that the OP has DOES need to be fixed and not left open. An alternative is to connect a check valve in that line so that air can flow in but fuel cannot flow back out as it is doing now. (The check valve also prevent fule leakeg in case of a rollover.) And, then on the other side of the check valve, a hose should be run to a filter that is located well above the tank to keep dust and other crap from being sucked into the tank, as air is drawn in while the tank is being drained in normal operation. The opening into this filter should point down or be shielded so that water cannot as easily enter the filter The charcoal cannister served this filtering function amongst other things.
 
No. The pictured vent IS the tank vent. Mopar never used vented caps. The 70's / later caps are called "pressure vaccuum" and are not meant for vent. They are only to relieve extreme pressure in the tank

And the line MUST be left open if nothing else is done, as it IS the only (original) vent.

That is, the tank is a completely sealed system

69/ earlier were vented by an open line to the filler neck

70 / later evap emissions equipped were vented through the 1/4 line going up front.

On cars with the line "still present" (and unused) going to the front, you can simply connect a hose down, say, in the wheel well to take care of what little over surge there might be. Some guys have plumbed them into the filter bonnet same as the PCV vent.
 
I don't have much luck interpreting close pics. Only thing I recognize is a leaf spring eye.
I will mention that some models have additional tubes for California emissions that not every owner would be familiar with.
Good luck with it.
 
Thanks for the tips, will be checking again tomorrow . Took about a 200 mile trip filled up again , no spill. Ummm
 
67Dart273 said:
No. The pictured vent IS the tank vent. Mopar never used vented caps.
Click to expand...
Not exactly true but may be so on the mid/later A bodies. My dad's 1964 880 wagon (or maybe it was the '61/) used a vented cap; he lost it and put on a non-vented cap, and the tank was crunched in from the suction......
 
67Dart273 said:
No. The pictured vent IS the tank vent. Mopar never used vented caps. The 70's / later caps are called "pressure vaccuum" and are not meant for vent. They are only to relieve extreme pressure in the tank

And the line MUST be left open if nothing else is done, as it IS the only (original) vent.

That is, the tank is a completely sealed system

69/ earlier were vented by an open line to the filler neck

70 / later evap emissions equipped were vented through the 1/4 line going up front.

On cars with the line "still present" (and unused) going to the front, you can simply connect a hose down, say, in the wheel well to take care of what little over surge there might be. Some guys have plumbed them into the filter bonnet same as the PCV vent.
Click to expand...
So if that is the vent line and then goes back to the filler only, then the cap has to be vented on the 69/earlier cars....there HAS to be a vent to open air, Del. The tank HAS to fill with air as the fuel is drawn down; it can't work any other way.
 
And to the OP, be aware that an open line into the tank is a good source to draw in dirt/dust if you drive on any dirt/gravel roads. And, it will be a source of fuel spillage in case of a rollover. That is the reason to add the check valve inline and filter; I don't care if others just leave it open; in my cars with this situation, they get some sort of check line and filter. I've done it on race cars (which is perhaps why I think about the rollover situation) as well as street cars. In later cars, the EVAP systems (with the charcoal canisters) take care of these 2 issues.
 
nm9stheham said:
So if that is the vent line and then goes back to the filler only, then the cap has to be vented on the 69/earlier cars....there HAS to be a vent to open air, Del. The tank HAS to fill with air as the fuel is drawn down; it can't work any other way.
Click to expand...

You still don't get this. LOOK at the diagram. The 1/4" line IS the vent. The 1/4" line connects to the top area of the filler neck, comes up, then back down, and IS OPEN inside the rear frame rail. that IS the vent, end of story.
 
You're right, now I see it....dropping under the trunk seal, NOT going back into the tank. I mistook the trunk seal for the top of the tank...duh....
 
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