Fuel Tank Breathing

[Tim Kay]

Can't seem to resolve the smell of gas fumes due to the system I have installed.

What are you guys doing to allow the fuel tanks to breathe? What is a solution to keep fuel from exiting the breather tubes? Where are breather tubes being installed and ventilating to?

Under hard braking, hard cornering and when tanks are full I have fuems due to fuel forcing out of the breather tubes. Tanks have foam to help the sloshing yet fuel still exits the breather tube.

Tim

 

[Tim Kay]

Pics of my setup

 

[Pat Buckley]

Tim, did you do this because it took a long time to refuel?

My CAV is a PITA to fill - takes forever, which allows too many specatators with their dumb questions.

I ran a check valve from the fitting on the back of my fuel bladder, but it doesn't seem to help much.

 

[Tim Kay]

Pat, my breather line does not help the filling time. I hear what your put'n down about the time it takes to fill which allows more attention from on-lookers. :laugh: I still fill with my hand on the pump nozzle squeezing small amounts of gas in at a time :thumbsdown: Does your check valve eliminate any fuel getting by it?

The clear breather tube exits by the filler cap via a roll over valve. The ball check within the valve is not sensitve enough and allows fuel to get by.

I am considering sealing the existing breather and weld in a breather tube up higher in the filler neck but not sure that will help any when the tank is full or near full or at anytime fuel surges up into the filler neck.

 

[Randy V]

Do you have any Russell or Earls steel braided hose in the system?

If so - that may be your problem... Not sure why, but they've gained a reputation for smelling. Not leaking mind you (at least not perceptible amounts) but just smelling.

I always use Aeroquip hose and fittings. Never a problem or a smell...

 

[Scott Calabro]

Hi Tim,

875 fills up as fast as I can pump it in.

You have a different filler pipe than I do.

Mine is a piece of mandrel bent pipe, not the fabbed piece you appear to have.

My "vent" does not go overboard as such. The small clear line you show (mine is 3/8" FI hose) goes right to the top of the Tornado supplied filler neck, and back into the tank.

The cap will vent vapors at a preset D/P.

Best,
Scott

 

[Mudgey]

Hi guys, I have never seen any issues with using this concept of filler system, the breather exits above the end of the nozzle so to eliminate the need for any air to have to fight past the fuel entering the tanks.

Ive always thought the filler caps allow enough breathing as to not need seperate breathers.
I know i'm stating the obvious, but some people (including myself) overlook these things, but have you re-checked all the jubilee clips, the other option is leakage past welds and the possibility of fumes entering the cabin from the external breathers themselves?

Regards,
Mudgey

 

[Tim Kay]

Scott and Mungey, thanks for the input.

I have modified my fillers from Tornado's design due to new fuel tanks and I was having issues of surging fuel clear up to the filler cap and seeping past.

So I added a locking fill cap under the GT40 style cap to eliminate that problem. It no longer breathes the way Mudgey suggest.

I removed and replaced the jubilee clamps to assure seal.

Big Foot, I will take note regarding the stailess lines.

 

[Tim Kay]

I bought a fuel vent valve, (http://64.202.180.37/files/cap.pdf pg 15) installed externally at the top of the tank. One road test so far seems I have resolved the issue I had with the smell of fuel.

My suspicion is the new vent valve is quite a bit more sensitive than the roll over valve previously installed. The orifice is smaller and the ball inside seems to seat\seal a bit more aggressively. :thumbsup: