No fuel tank release valve for pressure?

Ki Ki

Ki Ki

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So our new to us outboard Johnson 30 horse is connected to a fuel tank that's 6 gallons. Every tank on the cap before this one had a valve for pressure. This cap is solid and the tank releases a lot of air/ pressure when I open it on hot days. There's a little fuel gauge on it, but I don't see a valve at all? What's the deal here- is that possible?
 
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Fed

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Re: No fuel tank release valve for pressure?

There has to be a valve somewhere to let air in but not necessarily let air out.
Is the talk designed so that you can't fill it right up?
 
MH Hawker

MH Hawker

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Re: No fuel tank release valve for pressure?

IT sounds like you have one of the new tanks with the pressure caps, Their not doing very well in most cases. If you can find a new old stock cap change it out.
 
Ki Ki

Ki Ki

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Re: No fuel tank release valve for pressure?

MH Hawker said:
IT sounds like you have one of the new tanks with the pressure caps, Their not doing very well in most cases. If you can find a new old stock cap change it out.
Click to expand...

Can I buy a valved cap? Any harm in going from no valved sealed screw on cap to valved?
 
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R

Ray1958

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Re: No fuel tank release valve for pressure?

No harm. The problem is that the new cap was designed to vent. It has failed to work reliably. all you will be doing is replacing a part that was poorly designed to a cap that has proven to be effective.

Ray
 
MH Hawker

MH Hawker

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Re: No fuel tank release valve for pressure?

No problems at all. Some genius in the EPA decided that boat tanks needed the same type of vent system that cars use, its a pressurized tank until fuel is drawn into the motor then a vent opens to let the fuel flow in, while it sounds like a good idea, like most things it dosnt work especially well with the older motors. Right now if you can find a new old stock fuel cap it fixes the problems or a lot are doing mods to the existing caps.
 
H

Home Cookin'

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Re: No fuel tank release valve for pressure?

Mine don't have vents at all. Neither did my old metal tanks growing up. Just loosen the cap when using the motor. It's not that complicated.
 
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lrak

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Re: No fuel tank release valve for pressure?

I'm guessing you have an OMC/BRP "DuraTank" that is more than ten or less than two years old. I think they are the best 6 gallon outboard containers available. The ones more than about ten years old were not vented. They blow up like a balloon in the sun and shrink back down at night. I have two that have been doing that for over twenty years with no harm. I suspect one reason I've never had any ethanol/water issues is because no rain or humid air gets into the tank. About ten years ago they changed the connector design so that it opens a vent in the connector when you plug the hose in. You have to disconnect the hose to seal the tank. About two years ago the EPA mandated that all fuel tanks only vent at a certain pressure, so now they are sealed again.
 
Ki Ki

Ki Ki

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Re: No fuel tank release valve for pressure?

lrak said:
I'm guessing you have an OMC/BRP "DuraTank" that is more than ten or less than two years old. I think they are the best 6 gallon outboard containers available. The ones more than about ten years old were not vented. They blow up like a balloon in the sun and shrink back down at night. I have two that have been doing that for over twenty years with no harm. I suspect one reason I've never had any ethanol/water issues is because no rain or humid air gets into the tank. About ten years ago they changed the connector design so that it opens a vent in the connector when you plug the hose in. You have to disconnect the hose to seal the tank. About two years ago the EPA mandated that all fuel tanks only vent at a certain pressure, so now they are sealed again.
Click to expand...

That's exactly what it is! Duratank and I think came with the engine in 95 for a Johnson outboard.

So this is a good tank? Just leave it alone eh? Sounds like the pressurization is released through the hose valve and not an independent valve on the cap?
 
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lrak

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Re: No fuel tank release valve for pressure?

IMO its a very good tank. Just crack the fill cap to reduce pressure before attaching or removing the hose so no fuel squirts out if you slip up while connecting. Don't worry if the tank swells. It will be fine. There is one way vent on the hose connector that allows air in as fuel is sucked out.
 
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Ki Ki

Ki Ki

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Re: No fuel tank release valve for pressure?

lrak said:
IMO its a very good tank. Just crack the fill cap to reduce pressure before attaching or removing the hose so no fuel squirts out if you slip up while connecting. Don't worry if the tank swells. It will be fine. There is one way vent on the hose connector that allows air in as fuel is sucked out.
Click to expand...

Thanks very much! I usually don't disconnect the fuel line ever. Should I?I do at the end of the season when it gets winterized, but that's it.
 
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lrak

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Re: No fuel tank release valve for pressure?

I have two tanks and switch between them. When a tank is almost empty, I slow to idle, pump up the primer bulb, pull the hose off the old tank, plug it into the full tank, and continue on my way. Otherwise I probably wouldn't ever disconnect...
 
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