Fuel tank vent question

[slow91fj90]

After searching and reading a bunch Im getting more confused. While setting up my fuel system for the EFI, I noticed the previous owner had no vent hooked up on the tank, he had a hose just looping back into tank. I never noticed gas smell or tank leaking and stuff like that. Now I after installing the high pressure and return to the tank I still have a empty slot for a vent. Im not sure what to do because I dont have a charcoal canister. Can I just run a hose to a breather up high or similar?

Also how do I tell if I have a vented gas cap?

Thanks

 

[slow91fj90]

Oh and I forgot, I have the 23 gallon tank that BC sells if that helps.

Thanks

 

[slow91fj90]

Still not sure what to do about this, the more I read, the more Im getting frustrated. Can I just cap the vent? Since my truck is a 77 it has the vent tube with the filler? Im at wits end over this stupid thing. Need help;D

 

[Viperwolf1]

You need some kind of vent. Either a hose from the tank or a vented cap. The 5/8" vent in the filler tube is just the venr for filling the tank. It does no good once the cap is installed.

 

[slow91fj90]

You need some kind of vent. Either a hose from the tank or a vented cap. The 5/8" vent in the filler tube is just the venr for filling the tank. It does no good once the cap is installed.

OK thanks Viper, thats all I needed.

 

[JohnJohn]

The problem I ran into was the vented caps only vent air in, not out. My tank on a hot day would create enough positive pressure in the tank to cause my sending unit gasket to leak fuel.
I had just capped off the BC vent port on the tank vs. hooking up the charcoal system.

My short term fix was to drill a small hole in my gas cap.

 

[chuck]

viperwolf1 has it right. I built the tank with 2 5/16" tubes, 1 for EFI return and the other for a vent. Either will work for either. If you use a carb you can cap one but still need to use the other for a vent. If you use a hose up high that will work but if you keep your EB in the garage you will get gas smells. You can get a charcoal filter from most 80s-90s cars and trucks but the best setup is what came in the EB. The new tanks use -AN6 fittings for the fuel out and return, if you order it for carb we put a -AN cap on the return. I moved the vent to the rear of the tank and left it straight tubing.