To Vent or Not To Vent! - Lateral-g Forums

ccracin · #1 08-09-2011, 12:27 PM

That is my question! Cheesy, I know.

I am currently working on building a fuel tank for our truck project. It is based on Carl C's Vaporworx technology. He has been a great help. I have discussed this with him and others, but wanted to throw this out to the community. The fuel system uses the new Camaro internally regulated fuel pump module. I am fabricating the tank completely. I plan to have the fuel filler tube enter the top of the tank and extend down in to about 1-2" above the floor of the tank. This is in hopes of controlling fuel slosh back up to the vented cap that will be mounted flush in the bed floor. (Notice I said VENTED cap) I am certain the vented cap will provide the needed air to replace the fuel that is being used. My concern is that on hot days when fuel vapor builds inside the tank, if the fuel level is above the bottom of the filler tube I may have a problem. I don't want the fuel being pushed up the tube under pressure. This brings me to my question, should I add another vent? My initial thought was I could drill a small hole in the filler tube just under the lid of the tank and this should allow the vented cap to vent excess pressure to the atmosphere. (Second Pic.) Check out the pics below of my configuration. What do you all think? Any practical experiences to relate? Now is the time to do what ever it is I am going to do. Also, you can see the tank so far in my build thread. The link is in my signature below. Thanks.

wmhjr · #2 08-09-2011, 02:00 PM

Chad, since we talked last I thought about it some more.

I think you should have 3 vents with centrifugal spinning valves powered by an overdriven 10amp electric motor, isolated by 3 vapor barriers, run off battery power but with an automatic bypass to a secondary power source. That ought to do it

ccracin · #3 08-09-2011, 02:19 PM

Quote:

Originally Posted by wmhjr

Chad, since we talked last I thought about it some more.

I think you should have 3 vents with centrifugal spinning valves powered by an overdriven 10amp electric motor, isolated by 3 vapor barriers, run off battery power but with an automatic bypass to a secondary power source. That ought to do it

Sounds great, but now I am worried about cooling for the 10amp motor! Maybe a 12 amp pusher fan for the valve motor?

Stop helping!

**GregWeld** · #4 08-09-2011, 04:40 PM

The one I just finished I added a 1/2" vent from the top side of the tank near the fill tube and ran that up to near the top of the fill neck. That way any slosh went right back down and the fumes and pressure just went from the tank back to the tank if that makes any sense.

I think you absolutely need a vent. Or suffer the backsplash like an old chevy used to give you -- a nice douche of fuel...

Took this pic before I started welding up the sump.... NOTE my big red felt tip pen --- BECAUSE I WAS REAL TIRED OF THE FUEL DOUCHE!

This is the tank from my Nomad -- which began life as a carbureted car - so I decided that the EFI needed a sump etc....

The WidowMaker · #5 08-09-2011, 08:48 PM

if im reading greg right then i agree. plumb a line from the top of the tank to the filler tube. it helps when filling as well, especially if the nozzle reaches past the tube.

ccracin · #6 08-11-2011, 05:58 AM

Thanks Greg and Widow for the input. Bill, well.........

The fuel fill issue is one I was not taking into account. After Widow's comment and a conversations with Greg and Bill, A VENT IT IS! The filler cap is going to be in the bed floor which is going to be finished hardwood. I don't need it being douched with fuel. Thanks again.