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colemj · 20-09-2013, 12:55

We bought a new outboard and it came with a 3gal plastic gas tank. It has been many years since I have bought a dinghy gas tank and this didn't look very different.

However, there is a difference. The small vent screw on the filler cap has a rubber one-way duckbill valve in it. Air can enter the tank, but gas vapors cannot leave the tank.

The result in the 95* sun here is that the tank becomes a basketball and rolls around the dinghy. I end up unscrewing the main filler cap and leaving it loose on the tank to let the pressure out.

I have reread the instructions that came with the tank many, many times (I mean, how many instructions are necessary to operate a gas tank?). The instructions say to tighten the main cap after filling and loosen the vent cap. They also say that "As part of the fuel vapor retention system your tank will expand under internal pressures. This is normal."

REALLY? To turn into a beachball and roll around the dinghy is now "normal" for new tanks?

My question is: has anyone else experienced this, and am I doing something wrong?

Tomorrow, I am pulling out that rubber duckbill one-way valve.

Mark

s/v Moondancer · 20-09-2013, 12:59

You just have to keep the rain out...Cut the bottom off a coke bottle of the same diameter as the cap after you pull put the valve or just leave the cap a little loose.

Stu Jackson · 20-09-2013, 13:18

Sounds like the eviro-nazis struck again. About 10 years ago they came up with this "no spill" spout for gas containers (not fuel tanks) that was supposed to stop fuel spills when transferring fuel.

Only thing was they didn't work. Even Chcuk Hawley from West Marine tested them and said: "Nope!"

Only thing: they still make them and you can't buy anything else here in California. I'm glad I kept my old one, 'cuz it works. And I don't spill. There was nothing wrong with the old ones if you were the slightest bit careful. Now even those of us who are super careful HAVE to spill 'cuz the f*uckers just don't work.

Arrgh, progress...

Wraith_Mac · 20-09-2013, 14:10

I just checked all my 30litre tanks and none of them have that, not even the newer one.
They all have entrapped manual relief screws in the cap and none of them distort to the extent you describe when closed.
I have vented tanks by using a small screw in nipple [in the cap] and fuel hose to the top of the transom, this was with older tanks that did distort somewhat.
The vented cap stayed on the boat and was rotated to the tank in use. ie not used for transport.
Cumbersome but effective, I eventually plugged a fuel filter into the end of the hose, a Z14a I think, to give some protection at the transom, it worked well.
Cheers,
Mac

belizesailor · 20-09-2013, 17:56

Quote:

Originally Posted by s/v Moondancer

You just have to keep the rain out...Cut the bottom off a coke bottle of the same diameter as the cap after you pull put the valve or just leave the cap a little loose.

+1. You cant close tank vents here in the tropics without over pressurizing the tank. A rain "hat" is a good solution.

Sailmonkey · 21-09-2013, 07:06

We've got three of those new EPA compliant tanks. I've pulled the valves on two of them. The third is still unused.
Welcome to the new world of progress, where you can't pour your fuel without a special valve, outboard fuel hoses are now gray and über stiff and fuel tanks threaten to explode and shower you with gasoline!!!

colemj · 21-09-2013, 07:28

I am not closing the tank - I unscrew the vent screw in the top of the filler cap. The problem is that vent screw has a one-way valve in it that only allows air to enter the tank - not fuel vapors to escape.

I found yesterday that there is also a pressure-relief valve system in the tank that does relieve the fuel vapor pressure. However, it is set to relieve before the tank actually splits open, and not just when it becomes a beach ball.

The instructions say this is normal.

I think I will just pull out that one-way valve and the tank will operate just like our old ones. Also, the old tank fill caps fit on the new one, so that isn't a problem either.

I had just never seen this before and wondered if there was something wrong with our particular tank.

WraithMac - these tanks are designed to fulfill some type of California law that went into effect in 2012, so it is doubtful you have them where you are.

Mark

rebel heart · 21-09-2013, 07:31

I've had this little guy for a couple of years and have been quite happy with it. It's left out in the sun most of its life and gets torrential rain otherwise. They have difference sizes I think. My little 2hp four stroke goes through maybe 1/2 a gallon a week (~15 minutes of full speed a day).

Amazon.com : No-Spill 1415 1-1/4-Gallon Poly Gas Can (CARB Compliant) : Outdoor Power Gas Cans : Patio, Lawn & Garden

rebel heart · 21-09-2013, 07:33

It's the "green button makes it easy" models. The only problems I've read online is that from constant expansion eventually it fatigues the seams (in like 5 years) and leaks. If it's $20 and lasts for years of abuse, I'm good with that.

colemj · 21-09-2013, 07:48

Those aren't the kind I am talking about. Ours is similar to this: Amazon.com: Moeller OEM Choice EPA Portable Fuel Tank (3.2-Gallon): Sports & Outdoors

Mark

colemj · 21-09-2013, 07:54

I just looked at the FAQ section on Moeller tanks and saw this:

My new Moeller above deck tank swells up like a balloon. Why?
New EPA requirements have eliminated the manual open atmospheric vent on the portable fuel tank. The tank now is required to hold up to 5 psi. before automatic pressure relief. The portable tank can handle up to 15 psi.

I'm not sure you understand my situation. My tank cannot be venting.
It may vent during the diurnal temperature cycles of the day. You may also manually relieve the pressure before removing the cap by using the momentary push knob on the top of the tank. With the tank not being able to vent into the atmosphere under 5 psi, the EPA has calculated that the total amount of hydrocarbon emission reduction per portable fuel tank is acceptable. This reduction greatly reduces air quality issues.

Our tank is not a Moeller, so does not have that push knob relief. Even if it did, I wouldn't be sitting in the dinghy all day pushing it.

So it looks like balloon behavior is normal. It also looks like I will be removing that stupid valve!

Mark

zeehag · 21-09-2013, 09:27

and yáll laugh at me for rowing---lol .even my not chargeable torqueedo is better than the epa required bs on tanks now--good luck. rainhat on the vent is good. i did that successfully, have fun

my torqueedo doesnt charge because of some kind of connection defect ...

Wraith_Mac · 21-09-2013, 09:58

Quote:

Originally Posted by colemj

WraithMac - these tanks are designed to fulfill some type of California law that went into effect in 2012, so it is doubtful you have them where you are.Mark

I guessed that Mark,when you described the duckbill, then a couple of posters made it quite clear.

Hopefully we may never see that system here.
In some ways California is a separate planet I think.

For those who don't know, summers in Australia get a little warmer than many tropical regions will ever get. The humidity usually is a lot less though still a factor in fuel storage.
The temperature affects the tanks, the humidity affects the contents as the tank cools, which is why I vent my tanks through a filter as described above and not a rain hat.
Cheers,
Mac

belizesailor · 21-09-2013, 10:35

Quote:

Originally Posted by colemj

...

So it looks like balloon behavior is normal. It also looks like I will be removing that stupid valve!

Mark

Geez, they went and made fuel tanks complicated...glad I dont live in the land of excessive regulation anymore...most of my fuel tanks are just plastic tanks w holes in the cap for the hose...slightly oversized hole vents just fine.