Gas Smell

[Dream Weaver]

Hello,

I have a 1999 180 Sportsman with a gas smell I am hoping someone can help me get to the bottom of. The boat has been in storage (under a cover) for around two months, which is longer than it usually sits. The past couple of times I have been out to tinker with the boat, I have noticed a faint gas odor when I open the two access hatches in the back of the boat. Here, it is faint, and doesn't quite smell like raw gas.

Nonetheless, any gas smell makes me paranoid, so I kept searching. I remembered that a few months back, I had topped off the tank to go offshore for the day (the only time I have ever topped off the tank). This was the only time I have ever noticed a gas smell while running the boat, and I only noticed it the first half of the day, when the tank was full. This memory got me thinking about the vent hose and sending unit.

I decided to replace the gasket on my sending unit. I noticed that when I removed the deck plate right above the sending unit, there was a MUCH stronger gas smell, like that of raw gas. Hmmm.

Talked with a close friend of mine who works on boats for a living... he seems to think the vent hose might be compromised. I have checked all hose connections, everything seems legit and I can's see any obvious deterioration in any of the hoses. Also, this is a Moeller poly tank, so I don't think (knock on wood) it is leaking from the tank itself.

If anyone has any thoughts or experience with this particular issue I would greatly appreciate it.

Cheers

 

[drbatts]

Hoses are 23 years old, sounds like it's time to replace them. While the old ones are off, pressure test the tank to check for leaks.

 

[Hookup1]

It's possibly a tank leak. Earlier designs sealed the tank compartment to prevent fuel in the bilge. There is a plug in the aft compartment. If you pull the deck hatch use a plastic bilge pump to see what is in the bottom of the compartment. Be careful because it could be fuel.

Another possibility is the fuel hoses or sending unit. They are probably wishful thinks but could be a problem.

I have a 1997 Islander. Tanks have been tested OK but I plan to replace them in '23. They are overdue.

Some owners talk about inspecting them and repairing. This is a possibly if you are handy and have a place to do the work. For most owners the labor to pull the tanks and repair is about the same to do a straight replacement with new tanks.

 

[Dream Weaver]

It's possibly a tank leak. Earlier designs sealed the tank compartment to prevent fuel in the bilge. There is a plug in the aft compartment. If you pull the deck hatch use a plastic bilge pump to see what is in the bottom of the compartment. Be careful because it could be fuel.

Another possibility is the fuel hoses or sending unit. They are probably wishful thinks but could be a problem.

I have a 1997 Islander. Tanks have been tested OK but I plan to replace them in '23. They are overdue.

Some owners talk about inspecting them and repairing. This is a possibly if you are handy and have a place to do the work. For most owners the labor to pull the tanks and repair is about the same to do a straight replacement with new tanks.

Thanks for the reply! Do you think it’s possible to have a leak in the tank even though it’s plastic? Also, there is not a deck hatch on my model and I am unsure if there is a sealed tank compartment. The only ways to access the gas tank are through two, small, circular deck plates. If I were to replace the tank I would need to cut out the deck.

 

[DennisG01]

You mentioned you replaced the sending unit gasket but didn't specify if the smell is persisting?

It's unlikely the tank is leaking but also easy enough to verify by pressurizing it with a couple pounds of air.

Rub your hands on the tank's hoses and then smell your hands.

 

[Hookup1]

I don't have any experience with the plastic tanks. I would think they are somewhat leak proof. Pressure testing or automotive smoke testing is a good way to check.

I would wrap the hoses and the sending unit in paper towels and run the boat. Look at the towels. Paper towels are a good troubleshooting tool. But be carefull - this is raw fuel.

 

[seasick]

If yu topped of the tank and then covered it tightly, the sun will heat things up and the gas will expand. If the vent is in the filler cap of the vent is covered by the boat cover, fumes will get trapped under the cover. It is also quite likely that your tank hoses are a bit permeable in that liquid gas won't leak but vapors can.
If you removed the sender with the tank full it is very likely that gas leaked into the bilge. You were lucky if the gas didn't pour out.
That smell can last for a long time unless to rinse out the tank coffin with detergent and dry it out as best you can by leaving the deck plates off during dry weather.
The poly tanks do not corrode like the aluminum tanks.
I would keep an eye and a nose on the situation and if possible run the fuel level down a bit to see if the odor changes and go from there.
If you see liquid gas in the bilge, you should not use the boat!

 

[JJF]

FWIW: my Hydra-sports had a poly tank and I would get a faint smell of gas in the console. It didn't have that pungent gas smell, but it was definitely gas. Poly tanks are know to smell a bit. Having the boat under a cover will certainly exacerbate it.

In my boat it would faint during the season, but much stronger during the off season when the console door was constantly in use.

 

[Dream Weaver]

Thank you so much for all of your replies! I appreciate the suggestions. When I get to the bottom of it I’ll circle back and let you know what it turned out to be.

 

[PointedRose]

I’d disconnect the battery until it gets sorted

edit - seasick is right to disconnect from the battery switch (negative) not from the battery itself to avoid potential spark issue

 

[Fishtales]

I'd say it is time to redo the entire fuel system (lines to tank, tank itself and lines to the fuel separators and motors). 33 years is overdue if you ask me.

 

[seasick]

The poly tanks can last a long time but 33 years is a pretty long time
It is possible that Moeller still makes a poly tank that will fit. Is it the 82 gallon size?
If you go the route of replacing everything, replace the gas filler fitting too.
You may find additional issues when you pull the tank.

Is the tank deck lid screwed in or is the deck one piece with an outline of the tank area. The second config is more work to remove and reinstall

 

[Dream Weaver]

Unfortunately there is no deck hatch on the 180 model. I would replace everything if I could figure out how to access the tank. I think I would have to find a way to completely remove the console from the boat. The only quick access to the tank on the 180 model is through two, circular deck plates (one over the sending unit and one over the full hose intake).

 

[seasick]

Yup, it's a big job.

 

[SmokyMtnGrady]

So my boat was built in 08 and went into service new with me in 09 and around 2018 I had to replace both the fill and vent hose due to significant cracking and literally a few holes in the hose. I would replace your fuel hoses at a minimum.

 

[Recoil Rob]

I have a 2004 180 with the plastic tank. I also notice a funky smell when working in the hatches but have never seen any evidence of gas leakage on anything. Never any residue in the bilge. It doesn't smell like raw gas, more like old oil, like working under the hood of an old car. I thought it could also have been from servicing the fuel filter.