Fuel tank pressurizing

[Wetbuffalo]

So this has happened twice now. The ski is sitting in my garage during the day and I return home to fined the hull filled with about a half gallon of fuel. I have gotten really lucky that the carbs have held and not filled the cylinders and that a fuel fitting has just leaked.
My question is, should there be a valve that relives pressure. I am new to skis and this is my first one. The valve on the tank now has an arrow pointing to the tank and I am assuming that this lets air into the tank. Do I need another one to let pressure out? Any advice is appreciated!

 

[Vumad]

So this has happened twice now. The ski is sitting in my garage during the day and I return home to fined the hull filled with about a half gallon of fuel. I have gotten really lucky that the carbs have held and not filled the cylinders and that a fuel fitting has just leaked.
My question is, should there be a valve that relives pressure. I am new to skis and this is my first one. The valve on the tank now has an arrow pointing to the tank and I am assuming that this lets air into the tank. Do I need another one to let pressure out? Any advice is appreciated!

Is you return or vent line connected to a pickup for some reason? Fuel should only leave the tank through the pickups. It is not going to vaporize, condense and then settle in the hull. You should have a single pickup going to your carbs, or 2 pickups going to a selector, or 2 pickups each one going to one carb. If the fuel is not filling your cylinders, then the fuel is not coming from a line hooked to a pickup and then to your carbs, unless that line itself (or something in line) is leaking. Another possibility is that your tank is cracked.

 

[Quinc]

If anyone knows of a pressure release valve I wouldn't mind running one. My blaster builds up crazy amounts of pressure in the tank during the day.

 

[Proformance1]

Bring it down sometime when were riding ill take a look. Make sure all lines are zip tied

 

[Kny21]

You have a leaking connection or hole somewhere. Trace the whole system to find the source.

 

[Wetbuffalo]

The leak is coming from the stub line for the second pick up. I need to find some kinda pressure release and also properly cap the unused fuel pickup.

 

[Pro-pulsion]

When in the garage, if I have to work with the carbs at all I always break the seal on the fuel cap to prevent the tank from building any pressure at all. This will prevent the lines from constantly flowing pressurized fuel. If the ski is sitting, I typically always make sure my tank is full. Less airspace for pressure buildup. As mentioned, if you are having fuel escape the tank or lines then there is either a weak spot or failed component allowing the fuel to be forced out by the pressure. Fuel tanks, tank caps, lines and internal carb components should never leak under pressure and these machines do need the pressurized tanks to help with proper fuel supply. It is a similar concept to pressurized paint sprayer cans, the point is to help force the fuel out of the tank even when there is almost no fuel left rather than have the engine try to draw up sloshing low fuel levels on it's own. This way when you run the lines out, it is a total shut down of no fuel, not a gradual increasingly lean condition leading to engine damage.

 

[Fro Diesel]

The leak is coming from the stub line for the second pick up. I need to find some kinda pressure release and also properly cap the unused fuel pickup.

You need to remove the pickup from going down into the fuel. If there was only a single pick up on the inside you wouldn't have this issue

As the pressure in the tank increases it forces fuel out because you have the line going down into the fuel and it comes out your little stubby into the hull.
You capped it on the outside but you also need to remove it from the inside

 

[whitca]

I've had this happen a bunch over the years with various tanks. I got in the habit of just cracking the fill cap once home after riding to relieve tank pressure. Just remember to snug back down before the next ride.

Sent from my SM-N910V using Tapatalk

 

[Wetbuffalo]

Thanks guys for all the info! I am going to remove that extra pickup and crack the cap and hopefully this will stop.

 

[Pro-pulsion]

Just remember to snug back down before the next ride.

Agreed!!

I did a full tune up on a buddy's Blaster last year, forgot I had the cap loose while doing the carb rebuild and after I was done I loaded up and headed for the ramp. After I left the ramp, about 300ft out I saw a wave slap the cap and it moved! :O I reached as fast as I could but too late, a second wave hit it and spun it off filling the tank about 1/8 full of water lol. Needless to say but I'm saying it anyway...I had to get towed back in as the water did not like going up the fuel lines lol.

 

[Kny21]

Just looking at your setup I'd bet it's leaking where the npt plug is in the hose. You're going to need more than a ziptie to seal hose on threads vs traditional barb.

 

[Vumad]

When in the garage, if I have to work with the carbs at all I always break the seal on the fuel cap to prevent the tank from building any pressure at all. This will prevent the lines from constantly flowing pressurized fuel. If the ski is sitting, I typically always make sure my tank is full. Less airspace for pressure buildup. As mentioned, if you are having fuel escape the tank or lines then there is either a weak spot or failed component allowing the fuel to be forced out by the pressure. Fuel tanks, tank caps, lines and internal carb components should never leak under pressure and these machines do need the pressurized tanks to help with proper fuel supply. It is a similar concept to pressurized paint sprayer cans, the point is to help force the fuel out of the tank even when there is almost no fuel left rather than have the engine try to draw up sloshing low fuel levels on it's own. This way when you run the lines out, it is a total shut down of no fuel, not a gradual increasingly lean condition leading to engine damage.

That's great but one should at least be mindful of temperature, ventilation and ignition sources. it's better to fix the leak than to change how it leaks.

 

[JetManiac]

The leak is coming from the stub line for the second pick up. I need to find some kinda pressure release and also properly cap the unused fuel pickup.

Remove the unused barbed fitting in the CF internal fill and replace with the brass plug and problem solved.

 

[Proformance1]

you have used ski syndrome going on. LOL like i say stop down and well get you fixed up. If there was a bolt in one of the lines there are probably other issues. Use a viton vacuum cap on the barb and double zip tie it, or use a plug. Removing the pick up will help also. You do not need an over pressurization device. the check valve regulates that at about 5 psi.

 

[Pro-pulsion]

That's great but one should at least be mindful of temperature, ventilation and ignition sources. it's better to fix the leak than to change how it leaks.

Absolutely V, I was saying that only when working on the fuel system will I loosen the fuel cap to prevent pressurized from constantly running. I would never leave the cap open when the ski is just sitting between rides.