New Pressurized Portable Tanks

colbysmith

colbysmith

Active member
Guess the government in it's infinite wisdom now requires the small plastic 3 gallon tanks to be made so that fuel pressure can not escape. Ie, the cap lets air in so you don't have a vacume, yet it doesn't let the air out. Sooo, has anyone used one of these new tanks with the kickers? If so, did you have any problems with the pressure flooding the kicker? There are small fuel demand valves that can be purchased now to install in the fuel line. Is it necessary? Colby
 
I just bought one of these tanks with a new hose for my Tohatsu 6. Someone walked off with my old tank and hose sometime over winter. I assumed the new pressurized tank would create issues and I was not happy about the prospect -- but after using the tank on my dink for 3 days in Avalon I couldn't be happier.

The tank allows air to vent into the tank so a vacuum does not develop while at the same time expanding fumes cannot exit the tank, so it does create a bit of pressure. But, that worked to my advantage. In the past the engine would lose its prime if not used for a couple of hours. That is no longer the case. I assume the pressurized tank is keeping the engine primed -- even when left over night.

I thought the new pressurized tank was only a California thing. I can't speak to the need in Wisconsin, but in So Cal the pollution controls have worked wonders -- I grew up here and remember the glory days of orange air and purple sunsets (which we thought were cool as kids). Over the past twenty years air quality in the LA basin is substantially improved -- in spite of population growing by about 25%.
 
I don't have one of the new tanks, I have an older Moeller 6 gal. When I put it away for the winter in my shed it was about 2/3 full. I closed the vent and left it. When I went out to the shed a week ago, I found the tank quite swelled up (instead of flat it was quite round). There was wet gas on the side of the tank and underneath it. I thought the tank had split a seam, but it was that the internal pressure forced gas past the seals on the tank outlet. Opening the vent released the pressure and the tank sort of returned to its normal shape.

So having a tank that can't vent seems to me to be a very bad idea because:
- the tank may rupture due to vapor pressure (or the tank needs to be overbuilt)
- the seals in the fuel system can be damaged
- connecting and disconnecting the fuel line will lead to a spray of gasoline on nearby objects (say a hot motor).

The tank on my RIB sits in the sun all the time that the boat is in use or being trailered. It doesn't take long to see the tank start to swell from the heat if the vent is closed.
 
One thing that helps with the older tanks is to only fill them a little over 3/4 - maybe 5gal. in a 6gal. tank. Then with the cap slightly cracked put your knee on top and press down. With the tank "squashed down" tighten the cap. When it heats up it will return to normal shape and hopefully not over expand.

Its also good to vent tank before hooking up - not sure how these new ones work?

Regards, Rob
 
The new tanks have a warning label that states the tank may swell, but that it is designed to withstand that. I guess the Government has required most all the new stuff to be designed not to release fuel vapors into the air. (Blows that thought as soon as you open the cap a bit to release that pressure... ;-p In fact, I was just told by onlineoutboards.com the new regs are why all your new tanks, lines and connectors are so much more expensive. (see quotes below). The new tanks have a special valve in the cap that allows air in, but not out. Thus why a new fuel demand valve is on the markets. I was concerned that the pressure in the tank might flood the little kicker. Or at least that is one of the reasons they suggest buying the valve. But if I don't need it, why spend the $20 on it... Another question I have. The lines Tohatsu sales for this motor are 5/16". Would it be ok to use 3/8" line, or does that put more stress on the little kickers fuel pump? Finally, what about installing an inline or water separating fuel filter in the fuel line? There is an inline filter under the engines cover, but would it be prudent to add another filter upstream just after the tank? Or would that to put to much restriction on the flow?

"Thank you for your email. The part number you provided has recently superceded to the new EPA connector - 3GR702500M. The EPA factor is what has driven up the cost of all fuel related parts - including tank, line and connectors."
 
Just spoke on the phone with "Steve" at Onlineoutboards. He said the 3/8 line would probably be better than 5/16. Also said that with the newer tanks if they don't have a vent cap and pressurize, might be better using the fuel demand valves as with pressure it could actually push more fuel into the cylinder. (Talking about a small Tohatsu 6 here). So looks like I'll use the 3/8 line with the fuel demand valve. As for a fuel filter, any additional restriction in the line only makes the fuel pump work harder... but with good grade non ethanol fuel probably no reason for it. So think I'll just hook up my new kicker without an additional filter, but also plan on filtering the fuel before putting it in the integral or small external tanks.
 
Yeah, I'm wondering how the tanks in places like Arizona are going to do in the summer. Yeah, the government in it's infinite wisdom...
 
If the carburetor and fuel pump are in good condition, there would be no flooding or gas leaking into the crank case because of pressure in the fuel tank/line. For a 6 hp, I don't see any advantage to using a 3/8" over a 5/16" fuel line, but it would not be harmful. You have a float valve in the carburetor--once the bowl is full, no more fuel will come in. (This is all assuming that your engine is carbureted--with an injected engine--the injector pump is far higher pressure than would be obtained with the vapor pressor of gasoline.

I have had 2 fuel cans split in my life time--both were in the desert. Fuel leakage has been far more common.

As for the Smog in S. Calif. There will always be smog because of inversion layer. Having lived there over 50 years, and then out of that area for over 20 years, I realize the difference--and can still see it as I come over a pass into S. Calif. Basin.

Even Harry Pidgeon (second man to circumnavigate solo) described smog on returning from his first voyage to Hawaii. Something to the effect "I knew that I was nearing the coast of Los Angeles, by the brown pall which hung in the air". Also the old smudge pots used to keep the orange groves from freezing in the 20's and before. Smog was formally recognized in 1943, and in 1947 Caltech chemistry professor Arie Haagen-Smit and my father (at that time chief of R & D for S. Calif. Edison Co. ) worked on smog research and ways to cut the emissions from the power generating plants.

Even today the largest by far polluters are the oil refineries. The pollution by automobiles has dropped dramatically. I would suspect that the amount of pollution by 3, 6 and 12 gallon outboard fuel tanks is a very small percent of the total!
 
I just became the owner of one of these new tanks. I picked up a new Tohatsu 9.8 today at E Q Marine.

I examined the cap and the device that allows air in and holds pressure is a small rubber duckbill valve. (pencil eraser size) If this valve got something stuck between the rubber 'bills' it would no longer work and the vent would be open both ways. On this Tohatsu tank, there is a screw down vent valve on the cap. Instructions are to open this vent screw fully when running the engine, and close for transit. or storage.

The cap also has a 'click lock' release lever below the cap.
To relieve tank pressure, open the vent screw, then open the cap one 'click' by depressing the lever and turning slightly to the next click stop. This releases any pressure.

So, before hooking up or removing any gas hoses the pressure should be vented. This venting releases the very vapor that the gov wants the tank to hold.

WTF??
 
Larry,

1) The release valve you mentioned is there to avoid the problem Matt had.
2) The release of vapor pressure during re-fills or hookups can't really be avoided. However, the semi sealed tanks reduce the overall loss of fuel vapor over the long run as most tanks sit for fairly long periods of time between re-fills and disconnects.
 
Cal EPA estimates that the 9-10 million residential gas cans in California release about 87 tons a day of reactive organic gasses (what we used to call VOCs) -- the emission equivalent of a million cars. ROGs emit through permeation of the plastic as well as venting. The concern is not the occasional venting through 'burping' the tank (though that does release ROGs) but through the day long venting of old style tanks.

Cal EPA and US EPA could surely be taking us for a ride, but I've worked with regulatory scientists and -- unlike elected officials -- these folks know their craft.
 
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