Mild Gas Fume smell normal in aft storage?

[Tjames09]

As you are probably aware I recently purchased a new to me Legend 16 xcalibur. The boat is in immaculate shape and wasn't used much by the previous owner. I never noticed any smells when I checked the boat out or when we test it on the waters.

 

After trailering the boat home I noticed that the aft starboard side storage has a gas fume scent (the side the gas vent is on as well). The gas vent itself doesnt smell, just inside the storage. there isnt any tubes or anything in the storage, so Im not sure why it smells (just the anchor and some ropes). The actual aft transom area of the boat doesnt smell, and the entire floor in where the gas tank is is dry. I put my hand everywhere on the inside to make sure gas wasnt leaking, but the entire aft where the tank is dry, and both the storage compartments are also dry. So I dont think gas is leaking.

 

All the tubes and connections look good, and nothing is rotted or worn. Im somewhat concerned why there would be a fume smell, Ive read that older plastic onboard tank can emit a bit of an odor, the boat is 2011.

 

Im fairly certain theres no leak, but Im thinking its something like a weak connection somewhere causing a bit of a fume leak.

 

I called a bunch of marinas but everyone's slammed and booking like 3 weeks out now, which is fair considering its the beginning of the year. Im not sure if anyone on here can help, or offer some assistance. I dont know enough to start really tinkering around.

[Fisherman]

Maybe someone spilled gas there recently and it's just slowly evaporating. Leave it out on a windy day to clear the smell and see what happens.

[AKRISONER]

my experience is that every year when we open up the cover on the boat after being stored all winter there is always a smell. Im guessing its simply from the evaporation out of the tank that happens over the winter. the smell just gets trapped under the tarp.

[DanD]

See if any of the local garages have an EVAP test machine AKA a smoke machine. If the boat were here, I'd attach the smoke nozzle to the fuel tank's vent tube and then start pumping smoke into the fuel system.

Stand back and watch for smoke; the machine produces what looks like theatrical smoke. It also has a gauge that shows you the amount of leakage, if there is any. This machine is rated to detect a pinhole as small as .010".

We also use an inert gas to supply the 2-3 psi of pressure into the system, so there's no chance of explosion or excessive pressure to hurt anything.

Like I said hit up the locale shops; if there's vapor leaking from somewhere it shouldn't be this machine will show you it.

 

Here's a demo vid for a Snap On machine; close to what I have here in the shop.

 

Dan.

 

[Tjames09]

See if any of the local garages have an EVAP test machine AKA a smoke machine. If the boat were here, I'd attach the smoke nozzle to the fuel tank's vent tube and then start pumping smoke into the fuel system.

Stand back and watch for smoke; the machine produces what looks like theatrical smoke. It also has a gauge that shows you the amount of leakage, if there is any. This machine is rated to detect a pinhole as small as .010".

We also use an inert gas to supply the 2-3 psi of pressure into the system, so there's no chance of explosion or excessive pressure to hurt anything.

Like I said hit up the locale shops; if there's vapor leaking from somewhere it shouldn't be this machine will show you it.

 

Here's a demo vid for a Snap On machine; close to what I have here in the shop.

 

Dan.

 

 

 

Do you mean the vent tube on the exterior starboard side of the boat? the little screw cap? Is this system okay to be run through gas?

 

Thanks for the advice though, should I be checking any mechanic or just marine.

[irishfield]

My 2150 Baron has always had a "gas" smell when I open the floor rod storage door. Never been a hint of fuel in the bilge or any suspected leaks. I have had the entire floor out when eradicating the mice and when doing so confirmed there is zero leakage from the fuel tank. I think it just permeates through the plastic fuel tank and hoses.

[Old Ironmaker]

I have found if the tank was 100 filled in the Fall before storing when the temps go up in the spring expansion will cause some fuel to leak out the vent, sometimes if it gets really warm it can spirt out the vent as well. Air it out and see if it dissipates. If not follow our automotive Guru DanD's advice and take it to your auto mechanic for a leak test.

[Tjames09]

This may seem like a silly question, but can this vent be opened and closed?

 

[Old Ironmaker]

Looks similar to my vent James. Like any common vent valve it will open fully under X amount of pressure and close to normal position again. The fuel system has to be vented or you will never fill the tank. Mine was plugged up and I couldn't fill the tank with fuel properly.

[DanD]

 

 

Do you mean the vent tube on the exterior starboard side of the boat? the little screw cap? Is this system okay to be run through gas?

 

Thanks for the advice though, should I be checking any mechanic or just marine.

 

Yes the exterior vent; disconnect the hose to the vent and attach the smoke nozzle to the hose.

Yes again, this is just an inert vapor made up of nitrogen gas; it will not hurt anything. It would be best to test the system with a small amount of gasoline in the tank; more room for the smoke to find a way out and show you if there's a leak.

A lot of automotive shops now have these smoke machines.

 

Dan.

[G.mech]

There have been lots of reports of this phenomenon known as "fuel hose permeation" in the last few years. Some of the multitudes of the additives in modern gasoline can actually leach right through the walls of the fuel lines especially when the fuel sits stagnant for any period of time and result in the 'gassy' smell. It is common in applications such as in boats, hot rods, etc that sit in storage in the off season. If you run your hand along the length of the hose you will likely be able to smell it on your hand after. They say it's not really a big deal and that the hose isn't really leaking fuel or breaking down or anything but some of the molecules manage to sneak through over time. The only way to solve it is use 'low permeation' fuel hose. The high pressure fuel injector hose or MPI hose is considered low permeation but it costs more than regular fuel line. The low permeation hose should be marked SAE 30R9 while the regular hose will SAE 30R7. Most boat builders have been using low perm hose for a few years but without checking it's hard to say.

Edited May 4, 2017 by G.mech

[Tjames09]

There have been lots of reports of this phenomenon known as "fuel hose permeation" in the last few years. Some of the multitudes of the additives in modern gasoline can actually leach right through the walls of the fuel lines especially when the fuel sits stagnant for any period of time and result in the 'gassy' smell. It is common in applications such as in boats, hot rods, etc that sit in storage in the off season. If you run your hand along the length of the hose you will likely be able to smell it on your hand after. They say it's not really a big deal and that the hose isn't really leaking fuel or breaking down or anything but some of the molecules manage to sneak through over time. The only way to solve it is use 'low permeation' fuel hose. The high pressure fuel injector hose or MPI hose is considered low permeation but it costs more than regular fuel line. The low permeation hose should be marked SAE 30R9 while the regular hose will SAE 30R7. Most boat builders have been using low perm hose for a few years but without checking it's hard to say.

 

Ya its weird. So I opened everything up, and the smell went away, and was gone for a few days.

 

Now today, I haven't moved anything, kept everything open, but there's a bit of smell again. Its almost like something is periodically emitting a bit of a smell, but then it goes away.

 

The only thing I havent done yet is tighten down all the clamps on the hoses, but I dont think that will matter.

[Pigeontroller]

I removed my inboard fuel tank and had it pressure tested, and replaced all the hoses years ago cause of a fuel smell in my storage compartments...The smell was till there.

[scugpg]

Fuel permeates through hoses and most plastic tanks. But what your noticing is likely the temperature shift which causes fuel expansion and fumes escaping through the fuel vent. Does your boat have a diurnal or charcoal type vent system for the fuel? Or straight vent to the atmosphere?

[Old Ironmaker]

Does your boat have a diurnal or charcoal type vent system for the fuel? Or straight vent to the atmosphere?

Man, sounds like rocket science. Learn something every day. All I know is if mine is plugged I can't fill the tank with it not overflowing every few seconds. Diurnal? Not sure. How will I know Spooled?

[Tjames09]

Fuel permeates through hoses and most plastic tanks. But what your noticing is likely the temperature shift which causes fuel expansion and fumes escaping through the fuel vent. Does your boat have a diurnal or charcoal type vent system for the fuel? Or straight vent to the atmosphere?

 

 

I have no idea. The vent I pictured above is the exterior vent the boat has. the Attwood one. I have noticed it changes when the temperature changes, when it got really cool it smelt again. Theres three tubes that go into the tank: one large one for fill, one that goes from the tank to the motor, and one that goes to vent on the side of the boat. and then there's an electrical gauge for the fuel meter.

[scugpg]

 

 

I have no idea. The vent I pictured above is the exterior vent the boat has. the Attwood one. I have noticed it changes when the temperature changes, when it got really cool it smelt again. Theres three tubes that go into the tank: one large one for fill, one that goes from the tank to the motor, and one that goes to vent on the side of the boat. and then there's an electrical gauge for the fuel meter.

Depending on the age... that vent hose is likely straight to atmosphere with no cannister in between. That along with hose permeation (especially if your fill hose has fuel in it, as typically they aren't even A1 rated hose) will add to the effect whenever temperature or tank sloshing from transit happens.

 

Have a read... http://www.boatingmag.com/how-to/fuel-system-safety-tips

[DRIFTER_016]

Was working on my buddies boat today and when I opened the canopy you could smell gas.

The reason? Last week after cleaning the fuel tanks (plastic) we put them in the boat.

Tanks are empty and vents were closed. Fumes in the tanks just permeated through the plastic.

A little fuel fumes are normal when closed up.