Fuel cap and venting

[tngw1500se]

My boat has a fuel smell. I think its coming from the fuel tank compartment. It a 2007 175TXW with a 60HP mercury. I think it could be just the cap so I was going to just get a new one but I'm not sure what to buy. Got a link? Should the cap be vented? Mine has a "knob" on it but it doesn't unscrew. Also how is the tank vented if the cap doesn't vent? The fitting on the top of the tank seem like they're secure and not leaking. I don't see any wet gas anywhere in the hull or on the tank.

[bassfisher444]

You need a vented cap.

[Topwater 2]

That knob should screw open and closed, not completely off.

[tngw1500se]

I can't get it to move at all.

[tngw1500se]

Ordered a new cap. I'm thinking close it when trailering and open it on the lake??? Maybe open it in storage??? Can't find any info online.

[Mutt]

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[bassfisher444]

Mine vent stays open all the time just like any other gas powered vehicle or equipment I own.

[Extremeboating]

When trailering or storing the boat close it only needs to be open when you use it.

I agree with this for the most part but I would say when storing especially outside keep the vent cracked open due to expansion reasons due to the fluctuation in temperatures. You don't want to turn that thing into a bomb if pierced for whatever reason.

[tngw1500se]

I agree with this for the most part but I would say when storing especially outside keep the vent cracked open due to expansion reasons due to the fluctuation in temperatures. You don't want to turn that thing into a bomb if pierced for whatever reason.

I think that might be wise. My 5 gallon cans in my garage swell up when it's hot out. Sometimes they have a lot of pressure in them. Might be hard on a tank.

[Extremeboating]

I think that might be wise. My 5 gallon cans in my garage swell up when it's hot out. Sometimes they have a lot of pressure in them. Might be hard on a tank.

I've forgotten to open up the vent on mine on a really hot day and the moment I relieve the pressure I watch the tank lose a ton of space due to the swelling the expansion of the vapor the heat caused.

[Mutt]

The newer tanks have a pressure release lets off the pressure at 5 psi. leaving vent open is not good for storage. gas is hydroscopic in other others it absorbs moisture from the air.

[Extremeboating]

The newer tanks have a pressure release lets off the pressure at 5 psi. leaving vent open is not good for storage. gas is hydroscopic in other others it absorbs moisture from the air.

Those caps have been well known to fail and not relieve pressure at their 5 psi rating. They have also caused engines to grenade or just die while running due to causing fuel starvation. A lot of these new tanks on sale have received low rating due to the issues with the cap alone on what otherwise is a well designed product, which sort of sucks, but I digress. A lot of people have switched back over to a manual vented cap for the reason of vent failure alone.

If you let gas sit long enough to the point where it's going to be absorbing water or there is a doubt that it did absorb water then you should just get new fuel or you need to run your boat more often.

[Mutt]

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[Extremeboating]

What ever What do I know only a certified marine mechanic for over 48 years. Yes some of the caps fail but most of the time on failures is user neglect. But hey what do I know.

Look there's no need for hostility or to tout your Marine experience to me bud. I did automotive for over 20 years and hold various certificates and credentials even on a state level, but you don't see me using that to solidify my statements do you? Fuel tanks are fuel tanks and fuel will always be fuel. They behave the way they do based on their designs and reactions to their environment, that much I know we can both agree on. The EPA keeps trying to reinvent the wheel for better fume control, but their reinventions keep making things worse for the end consumer.

If you want to continue to promote sealed tanks with integrated "smart venting caps" then feel free to do so, hell it's what all of these retailers are doing now, but know that you are encouraging a layer of risk to the person you are recommending them to. I really don't have the energy to argue about this further nor do I want to turn this into some sort of pissing match, so as a whole let's just agree to disagree and leave it at that. If you still fish I hope to see you out on the Delta some time.

[Mutt]

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[Extremeboating]

You dont know a thing about me so go peddle your nonsense else wheres. people like you are who keep the industry in business.

And you speak like you know something about me. You think what you want chief. I'm not dealing with your conceited toolbag complex since you don't seem to know how to come at folks with common decency. We're done here. The OP has enough information to make his decision.

[tngw1500se]

I never thought this post would start an argument but it's the internet so it's expected so what about Trump, Biden, abortion & religion?

[FrancoCialone]

My first boat had a vent on the gas tank cap and to prevent the tank from expanding, would always leave it open. I also used "Don's Cocktail" to treat the gas and at the end of the season would winterize the engine and drain the gas tank empty and close the vent. Never had a problem in 17 years I had the boat.