4 vent tubes on my gas tank?

[DJ1967Dart]

So I have 4 vent tubes on the passenger side of my 70 challenger RT gas tank that have nothing connected. If I fill up the tank it will leak from these vents. Any issue if I replace the tank with a gas tank without the vent tubes? I believe the 4 vents were for a California emissions car. Can I just cap these off or does the gas tank need to vent?

 

[71Plym]

I have the same vent tubes on my 71 Cuda's gas tank, not a CA car. The vents connect to a vapour separator in the trunk; a silver tube on the passenger side. Fuel won't leak from the tubes. You should be able to cap all but one which is needed to vent the tank.

 

[DJ1967Dart]

Thanks 71, yes I capped all but one and that seemed to do the trick. If I replace the current tank with a tank without the vent tubes do you know how the tank vents?

 

[71Plym]

If you replace with a tank with no vent tubes you will need a vented gas cap.

 

[DJ1967Dart]

Makes sense - thanks 71.

 

[dongei]

Hang on to that gas tank as it is very very rare. It is for California cars. If you replace it and it is in good condition I would be interested in it for a spare.

 

[moparlee]

Hang on to that gas tank as it is very very rare. It is for California cars. If you replace it and it is in good condition I would be interested in it for a spare.

I don't think this is a "very very rare" gas tank. I have two '71 Challengers both purchased new in Michigan which have the four tubes.

 

[dongei]

My point ( not expressed well at all) is that if you want your car 100% and it came this way you can't buy a new one and finding a used one is difficult. I have been looking for three years for a replacement better than the one I have.

 

[scoose]

My point ( not expressed well at all) is that if you want your car 100% and it came this way you can't buy a new one and finding a used one is difficult. I have been looking for three years for a replacement better than the one I have.

I am going through this right now. I have the four nipples on the tank but the vapor liquid separator is toast. So that leaves me capping the nipples on the tank except one. That leads me to my question....

Shouldn't a hose be ran from the one uncapped nipple to a point higher than the tank to prevent leaking/spilling? Also, since I'm not routing it to the crank case I will have a gas smell all the time. How would I prevent this?

Is the real option to cap all 4 and run a vented cap?

 

[Steve340]

The vapour separator is also there to allow fuel to expand up the tubes and in to the separator. This will happen for example on a hot sunny day.
One of the lines would allow the liquid fuel to return to the tank. Off the top of the separator a line is in a round about way connected to the engine which sucks away any fumes.
I suggest you try and return the system to standard or at least copy the principal and your problems will be solved.
A standard gas tank cap is vented for pressure and vacuum but it is designed to work with the standard vapour system.
The standard system is well designed but it will not work of you do not have the whole system.
Only use bits and pieces of it obviously you will get some issue or other

 

[AUSTA]

So I have 4 vent tubes on the passenger side of my 70 challenger RT gas tank that have nothing connected. If I fill up the tank it will leak from these vents. Any issue if I replace the tank with a gas tank without the vent tubes? I believe the 4 vents were for a California emissions car. Can I just cap these off or does the gas tank need to vent?

The TA uses 2 tubes only supply & vapour return
It has a vent on the main filler pipe inside the trunk behind the gas cap this is then vented down through the trunk floor to the outside air or some are vented into the rear chassis rail which sounds like a bit of a recipe for disaster

 

[quapman]

All 70 (non-CA) cars vent into the pass. frame rail. I always found this to be odd and dangerous, too. 71 through mid 72 have the trunk tube and 73 went to the vapor chamber in the shock crossmember with the return line going back to the charcoal can & carb.

 

[Steve340]

That makes sense I think I read somewhere that 1971 was the year they started to get on to car manufacturers about emissions.
I looked in my service manual and it said all Chrysler products had the vapour separator system.
So I guess they also all had the 4 vent tubes.