Visit The Dirt Forum for More Information

Author Topic:   Fuel Cell Vent?
Kromulous
Dirt Forum Champ
Total posts: 796
posted April 20, 2005 02:54 PM  
Were switching from race gas to alcohol this year, our tank has to ports out of it. One for fuel supply, and a vent.

Now i need to run a return line, can i take the vent off and use that as the return line port, or do you have to have a vent and a return line?

If i need the vent, can you run a y-block and run two lines into one, before the filter? if so got any idea where to get one?

dirtbuster
Dirt Forum Champ
Total posts: 2007
posted April 20, 2005 03:09 PM  
You will need 3 lines, supply, vent and return.

All you need to do is get the correct size AN bulkhead fitting for your return line and its as simple as drilling another hole in the top of your fuel cell and installing the fitting with a plastic washer on either side of the bladder. Then hook up your return line.

I have seen some returns that go right back to the filter, but I think its better to send it back to the tank to release any aeration that may have occured through the pumping process. Just dumping it into the open space of the tank will allow any air trapped in the fuel to escape before being sent back to the pump.

sixwillwin
Dirt Freak

Total posts: 493
posted April 20, 2005 03:17 PM  
my fuel cap has a small vent, check that first before you go making more work for yourself..........

Kromulous
Dirt Forum Champ
Total posts: 796
posted April 20, 2005 03:18 PM  
Thanks Dirtbuster,

Is that risky at all, drilling a hole in the fuel cell and installing a bulkhead connector? I've never even seen the inside of one to know, i guess its some sort of rubber or plastic lining type deal in side there?

Obvously we'll drain all the fuel and let it air out and dry awhile before we do it.

Rat Trap
Dirt Maniac

Total posts: 129
posted April 20, 2005 03:19 PM  
speedway sales a filter that has AN fittings on it to hook your return line into. We've got one, this will be our 2nd year with it. Works great and you don't have to worry about running as much line, since you won't have to go all the way back to the tank. Heres the pn from speedway #91011742 you can get them different lengths, AN fittings, paper or steel elements. We are using the steel element one. 10"

Kromulous
Dirt Forum Champ
Total posts: 796
posted April 20, 2005 03:19 PM  
You know, i thought abou that, Siwillin, could you just put on of them little vents on the fuel cap?

Rat Trap
Dirt Maniac

Total posts: 129
posted April 20, 2005 03:25 PM  
if you use that pn i posted above to do a search you have to add -6, -8 or -10 to the end of it to come up with a result. (6",8",10")

dirtbuster
Dirt Forum Champ
Total posts: 2007
posted April 20, 2005 03:39 PM  
Most places we are at wont let you run a vented cap, and your vent line has to have a rollover valve in it. That way if you roll it there is not way for fuel to come out unless a fitting breaks off or the cap comes off.

No its not that big of a deal to drill it. I would empty the cell first. But, all you need to do is mark where you want it and drill a pilot hole. Keep in mind you will need to get a wrench on the inside of it so you'll prob want to keep it close to the opening or at least where you can reach it.
Next the easiest way would be to take the cap assembly off and then take the top of the can off so all you are dealing with is the bladder or top of the can itself.
Use a hole saw large enough to clear the hex of the bulkhead fitting and washers adn drill the can top. If you didnt take the top of the can off carefully drill trough the metal can top only, you dont want to cut into the bladder with the bigger hole size. Then drill out the bladder to fit the 'shaft' of the bulkhead fitting.
Then just put it together with the plastic washers against the bladder and tighten it down, and reassemble your can top and your done.

Thats the way most are done from the factory. RCI has made it really nice on their new ones becausethey use an oval shaped hole in the middle of the bladder with all 3 lines and the fill cap together. Then if you have to change a fitting you can pull the whole thing out and work on it instead of trying to get inside with wrenches.


mavrik82
Dirt Forum Racer

Total posts: 93
posted April 20, 2005 04:01 PM  
Another option.Run your return to the port being used for the vent, then drill the cap and put your rollover valve/vent on the cap

Iowamod20
Dirt Full Roller

Total posts: 73
posted April 21, 2005 12:45 PM  
You need more of a vent than just in the cap, I think #6-AN is recommended.

Don't trust the cap vent, it is small and collects dirt easily and can plug up. A guy I race against burnt up two motors before he found out his cap was plugged.

STREET16
Dirt Maniac

Total posts: 158
posted April 21, 2005 01:46 PM  
I like mavrik's idea. Anyone ever done it before, or have a reason not to?

Kromulous
Dirt Forum Champ
Total posts: 796
posted April 21, 2005 02:06 PM  
Me to, just scoping out a roll over valve in Smileys catalog.

mavrik82
Dirt Forum Racer

Total posts: 93
posted April 21, 2005 06:05 PM  
iowamod,I think you misunderstood me. I am talking about putting an a bulkhead fitting in the cap, and a rollover valve.

Ego Racing
Dirt Forum Champ
Total posts: 724
posted April 21, 2005 07:23 PM  
I think a 6an line connected to my cap would hinder it whenever I needed to opeen the cap to ad fuel. The tank is plastic and can be drilled to easy and be done right to try to mess around trying things. Just remember to drill it away from the pickup or the fuel will be splashing around and causing air to get into the fuel line.

STREET16
Dirt Maniac

Total posts: 158
posted April 22, 2005 11:49 AM  
quote:
Originally posted by Ego Racing:
I think a 6an line connected to my cap would hinder it whenever I needed to opeen the cap to ad fuel. The tank is plastic and can be drilled to easy and be done right to try to mess around trying things. Just remember to drill it away from the pickup or the fuel will be splashing around and causing air to get into the fuel line.

What we we're trying to say is put the full size roll-over valve / vent in the cap. then run the return line to where the roll-over valve / vent was originally located. There would not be a line going to the cap.

dirtbuster
Dirt Forum Champ
Total posts: 2007
posted April 22, 2005 12:32 PM  
I agree with Ego Racing, I dont know what vent you are going to use but on our car we have a -6 line running from the bulkhead fitting in the top of the cell with the rollover vent inside to the side of the cell with a filter in the end of it. So in that case you would end up with a line in the cap that might get in the way. I dont know, personally, I dont think it sounds like a good idea, but I have never seen it done or even whether it would pass inspection. That might be something to look into first.

Ego Racing
Dirt Forum Champ
Total posts: 724
posted April 22, 2005 01:29 PM  
I have only seen one car that the breather was not connected to the tank with a line, it was mounted to the vent fitting. As the car was going around fuel was making its way past the rollover valve because it was not rolling over and it was loosing fuel onto the top of the cell (just like when you fuel your lawn mower and the vapors wet the top of the tank) which ignited and burned the car and the driver was in the hospital for 5 days. A bulk head fitting with the plastic washers with a nut, a ballcheck rollover valve, breather and line is around $50. A heck of alot cheaper than a trip to the Hospital or loosing the car in a fire.

Kromulous
Dirt Forum Champ
Total posts: 796
posted April 22, 2005 02:09 PM  
I'm not sure i follow this correctly.

You got 3 ports:

In
out
vent

On the vent, you run a line (to where?) then a roll over valve and then the little filter deal?

dirtbuster
Dirt Forum Champ
Total posts: 2007
posted April 22, 2005 02:27 PM  
No the rollover valve is screwed on to bulkhead fitting inside the fuel cell. From the outside it just looks like a regular AN fitting. WE have a short piece of hose with fitting screwed on to that that runs to the side of the cell and has the filter in the end of it. The rollover vavle isnt in the line its inside the cell.

Back to the Archives