Fuel Smell in Floor

[Maxum88]

Hi all,
I have a '95 Mariah Talari 180 and I've noticed a fairly strong fuel smell in the floor/ski compartment. I've done some digging around online and read that plastic fuel tanks are known to breathe and you could have some odors. With that said, I scrubbed the compartment last night with some soap and rinsed it real good. Mariah's have an access hatch that I opened up and cleaned the part of the tank that was accessible and I did not notice any fumes there, nor are there ever any in engine compartment/bilge area. Obviously, the fumes are much stronger when I have the floor closed and the cover on the boat, I never really noticed, or bothered to check (yet) when she's in the water. I'm just second guessing taking it out right now until I know for sure I'm not going to ignite 15 gallons!

The tank is original to the boat. The fill hose is as well, I will be replacing that just due to age and I read that the ethanol can really raise hell on the older hoses. However, I feel that if it was a hose, I would be smelling it in the engine compartment.

Thanks in advance!
-Tim

 

[Chris1956]

Plastic fuel tanks do not allow fumes to escape. Replace the fill and breather hoses, and inspect the fuel gauge sender gasket (if you have a fuel sender) for leaking.

If that doesn't fix it, you may have a small leak in the tank.

 

[Maxum88]

Ok, thanks! I assume those hoses are pretty standard at a boating store and just go there with my length? My concern was if it was a hose or gasket, I would especially smell the fumes in the bilge and not so much in the floor at the front of the tank.

 

[JaCrispy]

You can see the date code on the fuel hoses. My 1988 boat still had 1987 date code hoses when I got it. lol

 

[Maxum88]

I checked the date on it last night...it looks like the hose running to the pump is from 2004...but the fill hose is original to the boat! I think I will just get the diameter and replace em all in one shot. Is the gasket for the sending unit fairly standard? I found that when dealing outside of the motor and outdrive, parts are a lot harder to research.

 

[JaCrispy]

The hose should have the size printed on it. The fill is prob 1 1/2". Did the gasket tear? If it's still intact you can apply sealer to it. Otherwise cut a new one out.

 

[Watermann]

If your covering the boat AND if the cover is over the fuel vent then the fumes from the tank will stay inside and of course sink to the lowest point they can find. It's very common to uncover your boat hop inside and get a whiff of gas fumes if the cover is over the vent.

 

[UncleWillie]

Plastic fuel tanks do not allow fumes to escape....

Permeability Standards that started in 2011 in most areas allow for 1.5g/M[SUP]2[/SUP]/Day to Pass through the walls of the tank.
It also allows 15g/M[SUP]2[/SUP]/Day to pass through the walls of the hoses, and 0.4g/Gal/Day to escape out the vent.
In Imperial terms, on a newer, typical recreational boat, you can expect to lose about an ounce of gas per day to evaporation.
On an older boat, the losses will be much higher. It was enough of a problem that laws were created to address it.
If these fumes are not well ventilated from the boat, they will collect at the lowest point, and it is possible that you will smell them.

The OP may have a leak, or not. It needs to be investigated.
After looking for the obvious, If a tank filled completely up the filler neck and one that is only 3/4 full show little difference in the amount fumes produced, the issue is probably due to permeation. If the super full tank smells to high heaven, you haven't found the leak yet!