Attwood 99CC035-1 Fuel Tank Carbon Canister Kit 28 Gal

This is the Attwood fuel tank carbon canister kit, part number 99CC035-1. It's the part that keeps your boat's gas tank from breathing raw fuel vapor out into the air. If you've ever popped a hatch on a warm afternoon and caught that strong gasoline smell coming off the tank, that's exactly what this canister is built to stop. It sits in the tank's vent line and traps the hydrocarbon vapor before it ever reaches the vent fitting on the hull.

Inside the housing is a bed of activated carbon. As the fuel in the tank warms up and expands through the day, it pushes vapor up the vent line, and the carbon adsorbs and holds those hydrocarbons instead of letting them escape. When the tank cools and draws air back in, the stored vapor gets pulled back toward the engine and burned off. It's a simple, sealed system with no moving parts to wear out, and it works quietly in the background every time you run the boat.

Boats built for the U.S. market have run evaporative emission control on their gasoline fuel systems for years now, and a carbon canister like this one is the heart of that setup. Whether you're rigging a new tank, repowering, or replacing a canister that's saturated or cracked, this is the kind of part that keeps a fuel system sealed and doing its job. A canister that's been flooded with liquid fuel or left sitting full of bilge water won't work right, so swapping in a fresh one is a common piece of fuel-system service.

This kit is sized for fuel systems up to 28 gallons and connects to a 5/8 inch vent hose, which is the common size on a lot of built-in gas tanks. The canister itself is compact at 11.6 inches long, 5.04 inches wide, and 4.01 inches tall, so it tucks into the run of vent line without demanding a huge amount of space. That low profile matters on smaller boats where every inch behind the console or under a gunwale is already spoken for.

Mounting is straightforward. Put it in the vent line above the fuel tank and keep it up out of any standing bilge water. The carbon bed has to stay dry to work, so you want a spot that sits above the waterline and away from spray. Use fuel-rated 5/8 inch hose on both sides and double-clamp each connection. That's cheap insurance against a weeping joint a couple of seasons down the road. Route the line so it drains back toward the tank instead of trapping liquid at the canister, and the part will do its job season after season.

How do you know when a canister needs replacing? A persistent fuel smell around the tank or the hull vent, a housing that's visibly cracked, or a canister that's been submerged or fuel-soaked are all good reasons to swap it. They don't last forever, and a saturated carbon bed stops adsorbing the way it should. On a boat that spends a lot of hot summer days tied up at the dock, the canister works hard, so it's a fair thing to check when you're chasing down a fuel odor you can't otherwise explain.

One thing to be clear about: this is a canister for gasoline vapor control, not a fuel filter and not a fuel and water separator. It doesn't touch the fuel your engine actually burns, so it won't help with dirty gas or water in the tank. If you're a rigger, a boatyard tech, or an owner doing your own fuel-system work, it's a clean drop-in for the emission side of the tank. And because it's an Attwood part, it's built to the same standard the company has held through more than a hundred years of marine hardware. When your old canister is done, this is the honest replacement to reach for.