Gasoline Fumes in Bilge

Repair or modification of Boston Whaler boats, their engines, trailers, and gear
InVision
Posts: 148
Joined: Sun May 07, 2017 7:04 am

Gasoline Fumes in Bilge

Postby InVision » Tue Jun 12, 2018 6:47 pm

I was getting ready to take in the 2004 Nantucket 190 for its re-power to E-TEC 150. On the preflight I noticed fumes (not real strong, but differently fumes) in the bilge when I was installing the plug.

Background: Last December I filled the fuel tank all the way up so as not to get condensation in tank. I have put less than a hour on it since. I did not see any actual gasoline in bilge . The boat is on a lift with a good sternward tilt. I checked the fuel gauge (deck) hatch, the access on the side by the tank cap, and the fill and vent hatch in the console, and [they] have so signs of any gasoline leaks. The tank is a molded plastic type.

I am assuming there should not at all be any fumes in bilge. I hate not having a separate overboard full tank vent.

Has anyone [diagnosed the cause of an odor of gasoline]? Would like ideas what to look for.

M

Proud owner of 2004 Boston Whaler 190 Nantucket ! ;)

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jimh
Posts: 4687
Joined: Fri Oct 09, 2015 12:25 pm
Location: Michigan, Lower Peninsula
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Re: Gasoline Fumes in Bilge

Postby jimh » Tue Jun 12, 2018 7:21 pm

It only takes a few drops of gasoline liquid to create the odor of gasoline. (Diesel in even worse. One drop on the deck and the boat smells like diesel for a week.)

Last December when you filled the fuel tank "all the way up", was there gasoline remaining in the fuel tank filler hose?

Typically the hoses used for the fuel tank filler hose and the fuel tank vent hose are USCG Type B, which means they are not designed to have gasoline in them at all times. They have some permeability.

I rather foolishly listened to advice once to fill my tank to "full" and ended up with fuel in the filler hose. The next day there was a clear and unmistakeable odor of gasoline coming out of the under deck spaces, most likely due to permeation in the filler hose or possibly vent hose. Since then, I NEVER fill the fuel tank anywhere close to "full" to avoid leaving any gasoline in the filler hose. Also, when adding fuel, I always try to impart a list to Starboard so any fuel in the filler hose (which is on Port side) will tend to drain into the tank rather than sit in some low spot in the filler hose.

InVision
Posts: 148
Joined: Sun May 07, 2017 7:04 am

Re: Gasoline Fumes in Bilge

Postby InVision » Tue Jun 12, 2018 7:56 pm

Thanks Jim. Your 100% right about not leaving gas in the fill tube.

I open the sending unit hatch and fill up until the tank is almost full. You can easily see with a flashlight were the tank level is.

I have read that with plastic molded tanks sometimes smell seeps thru.

I did check all hose clamps for tightness (some took a quarter-turn or so) and took a yard stick with a cotton swab taped to the end and ran every where I could around tank, hoses and fittings. It did not even have a hint of gasoline smell. The only sign of varnish I found was around the sending unit. No fuel. I think I will have them replace the gasket there.

M

Proud owner of 2004 Boston Whaler 190 Nantucket ! ;)

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InVision
Posts: 148
Joined: Sun May 07, 2017 7:04 am

Re: Gasoline Fumes in Bilge

Postby InVision » Wed Jun 13, 2018 3:37 am

Found this statement from Moeller:

- Permanent Fuel Tanks -

OPERATING TEMPERATURES
Moeller Marine fuel tanks are capable of operation within anambient temperature range from -40°F (-40° C) to 176°F (80°C).
IMPORTANT: Fuel tanks temperatures must be limited to 150°F (66° C) when not in operation. Processes that include dry heating
of the fuel tank beyond 150°F (66° C) should be discontinued immediately. Fuel tanks subjected to temperatures in excess of
150°F (66° C) when not in operation, could be considered as damaged, and may not be covered under the limited warranty.

PERMEATION
Permeation is a natural phenomenon of gasoline in a cross-linkedpolyethylene fuel tank. Permeation is the result of gasoline fumes escaping from the fuel tank, not the loss of liquid fuel. Several precautions need to be addressed when using across-linked polyethylene fuel tank:
  • Fuel (gasoline) vapors settle to the lowest point in the compartment, therefore, a means for removing the fumes is required.
    See ABYC Standards Section H-2 for specifics.
  • A covered boat will not allow these fumes to escape, so build up of these fumes is inevitable. Caution should be taken
    when a boats fuel tank contains fuel and is covered for anextended period of time. A boat cover should never cover
    the fuel tanks exterior vent fitting(s).
  • Fuel vapors will migrate to any compartment open to the fuel tank. The smell of fuel vapors does not necessarily
    mean that there is a leak in the fuel tank, but a closerinspection should be performed.
  • Fuel vapors may be absorbed by other objects located in compartments where fuel vapor may migrate.
Following the above precautions, across-linked polyethylene fuel tank will provide years of service.

Proud owner of 2004 Boston Whaler 190 Nantucket ! ;)

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Jefecinco
Posts: 716
Joined: Fri Oct 09, 2015 6:35 pm
Location: Spanish Fort, AL

Re: Gasoline Fumes in Bilge

Postby Jefecinco » Wed Jun 13, 2018 10:19 am

I believe your boat has a poly tank. Invariably poly tanks give off some minor gasoline smell. Your tank is probably vented via the fill cap. When filling the tank on our 190 Montauk I like to leave a little space for fuel expansion.
Butch

InVision
Posts: 148
Joined: Sun May 07, 2017 7:04 am

Re: Gasoline Fumes in Bilge

Postby InVision » Wed Jun 13, 2018 12:04 pm

As I stated I could not find any actual raw fuel. I just got back from dealer and after extensive tests no leaks were found. They think it is just the 15 year old Poly tank permeation smell has saturated the the bilge well and foam filling. I plan to wash out as good as I can the entire well under deck with soap and water. Leave the hatches open on a sunny day or two and maybe even blowing a fan inside to day completely. I feel better that I had a second opinion from a boat tech with 20 year experience.

BTW - the tech said the tank and well were extremely clean compared to other boats. He said he has seen he can't believe the boat is 15 years old !

We are preceding with the re-power, adding a Garmin 1042xsv and 9"x9" Lenco tabs and Led rocker switch.

M

Proud owner of 2004 Boston Whaler 190 Nantucket ! ;)

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Masbama
Posts: 149
Joined: Thu Oct 15, 2015 8:33 pm
Location: Mobile, Al

Re: Gasoline Fumes in Bilge

Postby Masbama » Thu Jun 14, 2018 10:36 pm

It's normal for these types of tanks to emit some odor after a period of non use. My 1999 Dauntless 18 had some and my 2003 190 Nantucket has a little once in a while if sitting on the trailer for a few weeks