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Fuel Tanks Leaking from Over Pressure
Posted: Sat Jul 11, 2020 2:09 am
by BWnewbie
Our Sport 15 boat has two 6-gallon Moeller plastic on-deck tanks. Fuel leaks from the fuel connector and the fuel tank level indicator. I have sealed both with Permatex Aviation Gasket Maker but to no use.
The tanks leak regardless of whether they are full or half-empty. The cause seems to be the EPA-compliant fuel tank filler cap. The cap will vent air in but has no means to release pressure except by depressing the top of the valve on the filler cap. If unattended the pressure builds and the fuel is forced out of any opening.
What is the solution to this?
Can I drill a small (1/64-inch) hole somewhere in the cap to allow pressure to continually vent out?
We find up to a half gallon of fuel on the deck!
Thank you

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Re: Fuel Tanks Leaking from Over Pressure
Posted: Sat Jul 11, 2020 9:51 am
by Jefecinco
Loosen the cap until it is almost off.
Re: Fuel Tanks Leaking from Over Pressure
Posted: Sat Jul 11, 2020 10:27 am
by Phil T
Been where you are. Drove me NUTS for an entire season.
Twist off that hunk of worthless plastic and replace it with the manual venting gas cap.
https://www.amazon.com/dp/B07GD1YXWN?tag=duckduckgo-osx-20&linkCode=osi&th=1&psc=1
Re: Fuel Tanks Leaking from Over Pressure
Posted: Sat Jul 11, 2020 12:00 pm
by jimh
Get new caps with manual vents as Phil suggests. Retain the EPA-compliant filler caps in case your boat is inspected by a zealot in some law enforcement agency.
I have not researched this carefully, but I suspect that the EPA regulations only bind the manufacturer to provide a non-venting cap when the tank is sold to consumers.
Unless there were some tag attached to the tank informing you the cap must never be replaced with a different cap, I couldn’t image you would be at risk of violating a federal fuel tank regulation and becoming a criminal. But if you see blue-lighted boats approaching, having the original caps could avoid an argument or worse.
Re: Fuel Tanks Leaking from Over Pressure
Posted: Sat Jul 11, 2020 2:06 pm
by BWnewbie
Thank you all so much. I will give your suggestions a try and let you know how it goes.
Re: Fuel Tanks Leaking from Over Pressure
Posted: Mon Jul 13, 2020 11:53 am
by biggiefl
Replace the cap and don't worry about the fuzz, they are not going to inspect your caps and there is no law against having an older non-epa tank like I use.
Re: Fuel Tanks Leaking from Over Pressure
Posted: Wed Nov 06, 2024 3:24 pm
by Compromise
[Adds comment to thread after it has been dormant for four years.]
I just bought a 2024 SPORT 13 with a Moeller fuel tank. The fuel tank leaked even when only half-full in [hot] August [weather].
The 2024 SPORT 13 boat self bails so the fuel not only makes a mess, but the fuel ends up in the river. I’m guessing the EPA didn’t consider that [outcome].