outboard fuel tank bulges in sun

[Robin3]

We have a Mercury 9.9hp 4 stroke motor on our RIB tender and it has a 3 gallon fuel tank that blows up like a ball in the sun. The original one that came with the motor cracked and leaked an West Marine, who suppliedthe motor, replaced it with one of theirs, which so far hasn't cracked but sure gets expanded. What do others do about this please, we carry our RIB in davits and the tank is left strapped in place? We still have an older style 6 gallon tank that came from a 2 stroke 9.9 Mercury we replaced, will this work with the 4 stroke engine or even could we perhaps just swap the vented cap on that one with the non-venting one on the current tank.

This strikes me as a legally mandated environmental 'improvement created mess that was ill conceived

[Orchidius]

This is perfectly normal, to a certain extent... If you slightly undo the cap, it should just hiss a little and after a while retake its normal shape.

Too much is too much though... Haven't ever heard about one exploding, but if it starts to look more like a ball than a fueltank, look into it.

It's heat related btw, but you probably figured that out by now too . Try covering it in some insulating material? Or taking it inside/out of the sun in any way?

[donradcliffe]

Sew a tank cover from white sunbrella.

[thinwater]

Wouldn't you love to set that bulging tank on a regulators desk and ask if that feels safe to them? Tell him not to worry if it starts to leak. Remind him that, like on a boat, if it starts to leak he has to stay there with it. Tell him it's OK to smoke; boats have ignition sources too and they never blow up due to gasoline leaks.

[Cheechako]

Originally Posted by thinwater

Wouldn't you love to set that bulging tank on a regulators desk and ask if that feels safe to them? Tell him not to worry if it starts to leak. Remind him that, like on a boat, if it starts to leak he has to stay there with it. Tell him it's OK to smoke; boats have ignition sources too and they never blow up due to gasoline leaks.

Crack the fill cap a bit if it doesn't have a vent.

[Robin3]

Originally Posted by Cheechako

Crack the fill cap a bit if it doesn't have a vent.

I have done that of course a couple of times, but always tightened it again before leaving the boat in the slip in case fuel leaked into the RIB. I have in mind putting a car windscreen sun shade over it too. However if the old tank is a valid option it would be a much tidier solution, even if contrary to the latest EPA (?) rules

[keepondancin]

i asked about compatibility yesterday with no response. Aparrently there are new fittings that are OEM that can't be used with older tanks and hoses, but, it appears that after market, replacement fittings will allow new engines with old tanks and vice versa. I would make sure the fittings are the same, and if so, switch the tank. I am trying to find if I can get a new hose to fit my old tanks and 2 stroke motor for just that reason, and the bulb is starting to loose flexibility. The new tanks and hoses are made of a less permeable material so vapors don't leach out, and so the tanks won't split. Guess your experience should send them back to the drawing board.

[Robin3]

Originally Posted by keepondancin

i asked about compatibility yesterday with no response. Aparrently there are new fittings that are OEM that can't be used with older tanks and hoses, but, it appears that after market, replacement fittings will allow new engines with old tanks and vice versa. I would make sure the fittings are the same, and if so, switch the tank. I am trying to find if I can get a new hose to fit my old tanks and 2 stroke motor for just that reason, and the bulb is starting to loose flexibility. The new tanks and hoses are made of a less permeable material so vapors don't leach out, and so the tanks won't split. Guess your experience should send them back to the drawing board.

I have not tried yet but it looks like the hose I inherited with the old tank ( it has quick type connectors at both ends) and it's associated defunct engine would fit the new engine, the connector does look identical to the engine end one on the new tank, where the tank end is a fixed screwed in fitting , The old tank is currently empty and I retained it only as a potential spare and possible storage for extra outboard or fuel for our small 1KW Honda generator. I can check the hose to engine connection easily enough next time on board and hopefully if that is OK then the tank will work if I put fuel in it. Obviously it will not have the pressure release gizmo in the fuel line that the new tank/hose has but It still seems it might be a better solution than keeping a gas filled football that slips it's restraining straps and rolls around the dinghy floor every time it expands in the sun ( temps here running daily around 95F )

I really do not want to have to store the existing tank below decks out of the sun, nor in a cockpit locker or lazarette.

[FamilyVan]

This is an awesome post. Open the vent.

Sent from my SGH-I547C using Cruisers Sailing Forum mobile app

[44'cruisingcat]

Yep, just loosen the vent a little. They're pretty good a letting the vapour out, while keeping the liquid in.

[Capt.Alex]

Originally Posted by FamilyVan

This is an awesome post. Open the vent.

Sent from my SGH-I547C using Cruisers Sailing Forum mobile app

FYI...The new generation of EPA approved outboard tanks do not have vents. Its best to be informed before posting snarky replies.

[Robin3]

Originally Posted by FamilyVan

This is an awesome post. Open the vent.

Sent from my SGH-I547C using Cruisers Sailing Forum mobile app

Would that be the vent that the new EPA regs had cause to be removed? If you can find one on my new style tank , I'll gladly open it.

[FamilyVan]

Yikes, good thing I'm not in the state's- gas tanks with no vents. No doubt you can vent them by cracking the lid.

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[Tayana42]

If you leave the full cap loose you can get water in the gas (particularly with ethanol) from humidity.


S/V B'Shert

[Robin3]

Originally Posted by Tayana42

If you leave the full cap loose you can get water in the gas (particularly with ethanol) from humidity.


S/V B'Shert

That is a good point if we do decide to go back to the old tank which does have a vent screw in the filler cap, although luckily our home marina fuel supply is still ethanol free