Question on fuel cell venting

[Hickey]

This tank has a sealed filler cap and the vent has a check ball in it. For the vent hose, many people run it up to the top of the cage, and then back down below the tank.

My question is: Does the vent line need to go that much higher, or will it work the same if I run it up and over this tube and back down below the tank?

 

[I Lean]

It does not need to go to the top of the cage. Just routed in a way that won't let fuel siphon out, no matter what orientation you land in.

 

[N-Smooth]

What you have pictured will work. It just needs to go past the side of the tank, higher than the tank and then to the other side and lower. I usually throw a loop into the end but that’s overkill.

 

[skippy]

I drill and tap my fuel cap for one of these and have never had one leak when im upside down. they are made for dirt bikes but they works great for everything

Motorcycle Gas Fuel Cap Valve Vent Breather Hose Tube Fit Dirt Bike Tank Tool / | eBay

6 Colors Fuel Cap Petrol Tank Breather Pipe Hose Fits Most 4-Stroke Pit Dirt Bike. Features: CNC machined & colour anodised & two-way breather. 1 X Fuel Tank Breather Pipe. Also the short pipe allows for easy turning of the fuel cap.

www.ebay.com

 

[Hickey]

I drill and tap my fuel cap for one of these and have never had one leak when im upside down. they are made for dirt bikes but they works great for everything

Motorcycle Gas Fuel Cap Valve Vent Breather Hose Tube Fit Dirt Bike Tank Tool / | eBay

6 Colors Fuel Cap Petrol Tank Breather Pipe Hose Fits Most 4-Stroke Pit Dirt Bike. Features: CNC machined & colour anodised & two-way breather. 1 X Fuel Tank Breather Pipe. Also the short pipe allows for easy turning of the fuel cap.

www.ebay.com

Are they a check valve of sorts?

 

[skippy]

Are they a check valve of sorts?

yes siree its the only form of breather I run on my moonbuggy and its been in many

 

[Hickey]

yes siree its the only form of breather I run on my moonbuggy and its been in many

What do you do for your diff vents?

 

[spaggyroe]

I used to run something like this on my buggy Jeremy. (for the differentials)

https://www.amazon.com/Universal-Breather-Closed-Differential-Bellows/dp/B00BWTB0WK

 

[Herzog]

I could be wrong but if you run the breather down below the tank you risk creating a siphon if you are leaning to the pass side and don't create an air gap. I've always ran mine up and loop back down just a little bit. I have a rollover valve inline on the breather but I think there's also one on the breather outlet of the tank.

 

[skippy]

What do you do for your diff vents?

I dont run diff vents on buggies.

 

[Hickey]

I used to run something like this on my buggy Jeremy. (for the differentials)

https://www.amazon.com/Universal-Breather-Closed-Differential-Bellows/dp/B00BWTB0WK

Those are my plan unless I come across a better plan.

 

[Hickey]

I could be wrong but if you run the breather down below the tank you risk creating a siphon if you are leaning to the pass side and don't create an air gap. I've always ran mine up and loop back down just a little bit. I have a rollover valve inline on the breather but I think there's also one on the breather outlet of the tank.

I think the check valve will keep it from siphoning.

 

[RockChucker]

I have a check valve in my breather and it’s routed up around the rollbar and down lower than the bottom of the tank. I’ve never had siphoning issues at extreme angles.

 

[N-Smooth]

Yeah I've tried really hard at making mine leak and it never has. People think it's bad driving but I'm just testing the fuel system.

Comp rules made me install a ball valve in the line as well but I've never even used it.

 

[Hickey]

Yeah I've tried really hard at making mine leak and it never has. People think it's bad driving but I'm just testing the fuel system.

Comp rules made me install a ball valve in the line as well but I've never even used it.

A ball valve in the breather line?

 

[N-Smooth]

A ball valve in the breather line?

yessir it's been required in all of the different comp org's I've taken part in

 

[Hickey]

yessir it's been required in all of the different comp org's I've taken part in

I guess that makes sense. I do have an extra ball valve, maybe I'll throw it in there.

 

[Gravy]

The rulebook in short course was the vent had to be routed like your diagram but in a 3rd dimension as well (X/Y/Z axis) in case of end over end or sideways rollovers. I agree that a ball valve is a good idea.

A word of caution on those dirt bike valves. I have first hand experience here.
The cheap ones can rust and prevent the ball valve from venting. Had a bike that wouldn't run periodically unless I vented the gas cap.
Swapped the valve for a brand name one and had no further problems. (The difference in price is about $3 LoL)