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View Full Version : Fuel cell vent?Need help!!



m glassburner
06-03-2004, 11:59 PM
Mine leaks a bit...How do you do yours?? ATL said to put loops in the line??Thanx for the help!! mike g. http://Forum.ImprovedTouring.com/it/smile.gif

Bill Miller
06-04-2004, 07:13 AM
Where is it leaking? Some sloshing/spilling is expected, especially w/ a full cell.

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MARRS #25 ITB Rabbit GTI (sold) | MARRS #25 HProd Rabbit
SCCA 279608

joeg
06-04-2004, 08:47 AM
I trust it connects to a tube that goes to the outside of the vehicle.

The exit spot on the body for this tube should be higher than the top of the cell.

I put my tube exits to the rear of the car (as opposed to either side)and use braided line with an AN bulkhead fitting through the rear valance panel so when not in use, the vent can be plugged with an AN cap.

Adding a loop in the line is OK; just don't "kink" it.

Greg Gauper
06-04-2004, 10:33 AM
Even cars with check valves can still slosh a bit of fuel.

I don't have a loop in my line, but I do have a longer than normal vent line run and I 'arched' it up about 12-18" above the cell, then ran it horizontally, then gave it another slight upward arch before turning down to exit the car (picture a sink trap turned upside down).

I've heard that a loop can trap fuel and prevent the vent from venting.

bill f
06-04-2004, 03:42 PM
When we installed a cell in the Mustang, we experienced overflow from the vent to the outside on a severe right/left/right sequence...Watkins Glen Bus Stop. After much coffee and midnight oil, we finally realized the problem.

It was solved with a loop and routing the vent line to the opposite side of the car before exit thru the body.

FYI, at constant lateral G load, the fuel will attain an angle of 45 degrees. With additional surge created by the additional momentum of moving fuel, the angle was much more severe. The solution was effective.

If the cell is leaking at the exit point of the fitting to the cell body (rotary cell), use additional o-ring seals to complete it. Also, additional pressure from the inside of the cell from expanding volume (heat) will violate the seals. The small rubber vent in the cap of the rotary cell sill allow air INTO the cell, not allow the expanding air OUT of the cell. Been there, etc.

We had to add an additional vent with inversion valve. It was this line that was spilling fuel in the corner.

Good luck.

Good racing.

Bill

06-04-2004, 10:45 PM
heres a good story for you guys. My close friends nick named me "Meat Bee Brightwell" after a trip to laguna last year, seems at buttonwillow I had fuel sloshing out everywhere like you did because of a too short vent tube, so being the crafty guy I bent a stainless 1/4" tube into a U shape that came thru my trunk floor, up the rear cage down tube, across the main hoop and back down the other downtube and thru the trunk floor to right next to the bottom of the cell. surely this would "solve all my problems" I bragged to my buddies. well laguna was a three day race with sat off for me in the scedule so I headed into santa cruz across the monterey bay from laguna to shoot the breeze with my home town buddies. sun comes around and im doing better than ever at the halfway point in the race and my engine just dies going down the strait, I know its fuel so after the race I start at the float bowl and work my way all the way to the fuel cap and it all clear, then I gaze at my shiney new vent tube in suspicion, could it be?.... upon inspection a "wood cutter bee" also known as a "meat bee" had stored what looked to be part of a hamburger in the end of my new vent tube while I was off enjoying a day off. theres got to be a moral there, just not sure what it is.

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Daryl Brightwell
ITA RX7 #11
NORPAC
ITA RX7 #77
SOPAC

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EP this summer



edited by Bud Light

[This message has been edited by 7'sRracing (edited June 04, 2004).]

evanwebb
06-06-2004, 12:20 PM
Keep in mind that the ball check valve in the fuel cell vent fitting doesn't actually act like a check valve unless the car is upside down. We also had the same problem you describe and we installed a low cracking pressure flapper valve in the vent line and it took care of the problem.

m glassburner
06-06-2004, 08:48 PM
Where did you get it?The one I have for my accusump cost @100$ mike g.