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Raw Gas Smell
https://www.smwebhead.com/phpBB3/viewtopic.php?f=6&t=13673		 Page 1 of 3
Author:  Bliss36 [ Sat Dec 20, 2014 11:09 am ]
Post subject:  Raw Gas Smell
Towards the end of last season we would notice a strong raw gas smell in the cabin after a cruise. Every time I noticed the smell I would pull the engine cover off and start sniffing around but could never pinpoint the source. Our last trip out to the beach it was really strong in the cabin so I removed all the screws and lifted the floor out from the mid cabin to find the smell to be really strong in that area(fuel tank). Also had our blower give up the ghost somewhere between the dock and the beach...helluva last day on the lake huh?

I went to the boat last night and lifted that same cover (mid cabin floor)only to be knocked over with fumes. The tank is nearly full, about 2 inches from top of tank and I don't see any wet spots. Anybody deal with this before? Do these tanks saturate over time and have to be replaced? Anyone smell their fuel tank area and have a gas smell? I notice Moeller now makes a low permeation tank...is that because their older ones had high permeation http://www.moellermarine.com/aftermarket/fuel_storage_tanks/permanent_tanks/

Since the smell is pinpointed to that area I'm trying to think of ways to test it.I brought the gas cap home to match the threads and make a fitting I can use to lightly pressurize the tank, use soap/water and check for leaks. I'm really hoping it's just a sending unit and not the tank itself because I'm sure that will be big $$. I did find an old post from Woggy718 where his fuel sending unit dumped fuel into his bilge on a trip...I really hope that's the problem.
Author:  acguy [ Sat Dec 20, 2014 12:21 pm ]
Post subject:  Re: Raw Gas Smell
I had a similar situation this summer. After every cruise we would shut down the engine and after we were stopped you could smell fuel in the cabin entry. I kept looking in the bilge and smelling down in the cabin bilge and nothing. After an hour of searching I had found the the fuel filters on both engine had loosened off. I did not install them the marina did prior to winter layup. I also found the O'ring on the fuel caps where very degraded and replaced them.
Is it possible that maybe your fuel vent line is plugged and your tank in becoming pressurized?
Author:  JeffLW [ Sat Dec 20, 2014 2:07 pm ]
Post subject:  Re: Raw Gas Smell
Does your boat have an inline fuel filter?
My boat had the same issue when I first got it. After checking everything I could think of, I too thought it had to be the tank. Then when I was running the engine after the first oil change I had my helper turn off the engine while I was looking in the engine compartment. I saw a couple drops of fuel drip from the inline fuel filter just after the engine shut off. It only did this every time the engine was shut down and it was only a small amount. Just enough to make fumes. There is some staining of the fiberglass just under the filter so I'm guessing this was happening for a while and the previous owner was lucky. :shock:

I changed the filter, checked all the lines/fittings and cleaned the bilge. No more drips after that. There still was a faint gas smell in the aft cabin that took some time to fade away.

Image
Author:  LouC [ Sat Dec 20, 2014 2:23 pm ]
Post subject:  Re: Raw Gas Smell
Sometimes the gasket for the sending unit will dry out and leak a bit especially when the tank is full.
Author:  Surface Interval [ Sun Dec 21, 2014 4:32 pm ]
Post subject:  Re: Raw Gas Smell
A while back Lou mentioned using blue paper shop towels under potential leak areas to help the source of a leak. The blue towel changes color when wet. I used this tactic last fall. Thanks, Lou. Ben, do you have enough fuel in the tank to cover the fuel quantity transmitter gasket and other fittings on the top of the tank? If not, then I wonder if you would be getting that much vapor and smell from that type of connection if the fuel tank vent is clear. Just a thought. Is the battery still in the boat? I'm sure you have it winterized, but you might be able to just turn the key on to energize the electric fuel pump and pressurize the fuel system on the engine. Maybe the paper towel trick might show a leak, or eliminate the engine fuel system plumbing. Is the tank set on the fiberglass hull or on any sort of pad that may absorb and hold fuel for a while? I did not notice on mine exactly how the tank was installed and supported.
Author:  Surface Interval [ Sun Dec 21, 2014 4:33 pm ]
Post subject:  Re: Raw Gas Smell
Sorry for the double post.
Author:  LouC [ Sun Dec 21, 2014 8:58 pm ]
Post subject:  Re: Raw Gas Smell
I used the blue paper towl trick trouble shooting water leaks in my old '98 Jeep. Worked like a charm.
Author:  Bliss36 [ Tue Dec 23, 2014 12:26 am ]
Post subject:  Re: Raw Gas Smell
acguy wrote:
I had a similar situation this summer. After every cruise we would shut down the engine and after we were stopped you could smell fuel in the cabin entry. I kept looking in the bilge and smelling down in the cabin bilge and nothing. After an hour of searching I had found the the fuel filters on both engine had loosened off. I did not install them the marina did prior to winter layup. I also found the O'ring on the fuel caps where very degraded and replaced them.
Is it possible that maybe your fuel vent line is plugged and your tank in becoming pressurized?

Sounds like we have a very similar situation as you described perfectly when and where we smell the gas. I originally thought it was the o ring on the gas cap because shortly after first noticing the smell I watched as the o ring fell into the water at the fuel dock when the dock hand spun the cap off. The smell continued after the o ring replacement and I did also replace my fuel filter because it looked a little damp around the seal ring but still the smell persists.
JeffLW wrote:
Does your boat have an inline fuel filter?
My boat had the same issue when I first got it. After checking everything I could think of, I too thought it had to be the tank. Then when I was running the engine after the first oil change I had my helper turn off the engine while I was looking in the engine compartment. I saw a couple drops of fuel drip from the inline fuel filter just after the engine shut off. It only did this every time the engine was shut down and it was only a small amount. Just enough to make fumes. There is some staining of the fiberglass just under the filter so I'm guessing this was happening for a while and the previous owner was lucky. :shock:

It does not have an inline fuel filter but it does have an inline fuel sensor for my FloScan fuel flow meter. I've checked around the sensor for dampness but it is a little awkward to check around so maybe Lou's blue paper towel trick that Surface Interval mentioned would help identify if that's the problem area or not
Author:  Bliss36 [ Tue Dec 23, 2014 12:49 am ]
Post subject:  Re: Raw Gas Smell
LouC wrote:
Sometimes the gasket for the sending unit will dry out and leak a bit especially when the tank is full.

I'm really hoping this is the cause simply because it might be the cheapest fix for a serious problem. I'm leaning towards this because I can't seem to re create the smell just sitting in the slip, it almost seems like I need the sloshing around of fuel to get the smell. With the fuel sensor being at the top of the tank it would make sense to need the fuel to slosh to make it happen.
Surface Interval wrote:
A while back Lou mentioned using blue paper shop towels under potential leak areas to help the source of a leak. The blue towel changes color when wet. I used this tactic last fall. Thanks, Lou. Ben, do you have enough fuel in the tank to cover the fuel quantity transmitter gasket and other fittings on the top of the tank? If not, then I wonder if you would be getting that much vapor and smell from that type of connection if the fuel tank vent is clear. Just a thought. Is the battery still in the boat? I'm sure you have it winterized, but you might be able to just turn the key on to energize the electric fuel pump and pressurize the fuel system on the engine. Maybe the paper towel trick might show a leak, or eliminate the engine fuel system plumbing. Is the tank set on the fiberglass hull or on any sort of pad that may absorb and hold fuel for a while? I did not notice on mine exactly how the tank was installed and supported.

I plan to use the blue paper towel trip in a few places, so thanks to you and Lou for teaching me that new trick! The gas level is about 2 inches from the top of the tank so not close enough to leak out of the sender if the gasket has failed. I plan on blocking the vent and lightly pressurizing my tank while spreading around soapy water to look for bubbles. This will at the very least help eliminate the fuel tank(hopefully). The gasket around the fuel level sensor is swollen so hopefully the bubbles will come pouring out of there. I would have to assume if it was the tank, and the tank is currently 90%+ full that I would see some sort of actual leak or puddle...I can't see the tank getting a tiny pinhole in it for no reason.

The boat is in heated storage so I can do key cycle fuel pressure tests but obviously can't start it. When I cycle the key to prime the pump I don't get the smell, which helped to eliminate suspicion of a leaking down injector after shutting down the engine. It's really hard to see what the tank is resting on but from what I can tell it seems to be sitting directly on the hull.

Once past these holidays I'll have a chance to get back to the shop and run some more tests. Hopefully it's something simple,easy, and cheap to fix but since it's a boat we all know that won't be the case :D

Thanks to everyone for the advice and I'll keep you posted on any developments.
Author:  LouC [ Tue Dec 23, 2014 9:04 am ]
Post subject:  Re: Raw Gas Smell
While the plastic tanks do allow some permeation what you are getting seems to be in excess of that. During Hurricane Sandy here in Long Island NY I had a collection of 5 gallon gas cans in the garage to keep the gen set running (no electric for 2weeks). There was little to no odor in the garage.
One thing I prefer about aluminum tanks is that there is really no odor with them, or should be none, and they have tabs welded on so they are easier to secure. Poly tanks won't corrode for sure, but there are other issues. Sometimes the fittings in the top of the tank strip out (spinning in the plastic) and the screws/bolts that secure the sending unit won't seal properly.
Back when I was going to install a gas fume detector, I thought I did smell something, in the ski locker of my bowrider. So I used the fume detector, moved it around, put it right where I faintly smelled gas, but it does not alarm when there is just a slight fuel smell. Your nose is actually more sensitive. All I had to do was very slightly tighten the screws for the sending unit. I do take up the tank hatch at the beginning of each season, to check that, and the hose clamps for all 3 hoses.
Author:  JeffLW [ Tue Dec 23, 2014 11:26 am ]
Post subject:  Re: Raw Gas Smell
Bliss have you replaced the fuel line in your boat at all? I've been reading that any fuel lines older than 2009 should be replaced with newer ethanol friendly hose.
I'm thinking I may do mine in the spring since they are 10 years old now.
Author:  Decision [ Tue Dec 23, 2014 1:50 pm ]
Post subject:  Re: Raw Gas Smell
We would get a gas smell in our previous boat (30' Doral Prestancia). This boat had 2 50 gallon aluminum fuel tanks, one on port side and one on starboard side.

The only time we would geta gas smell was when we filled the tanks full or real close to full, fill the tanks 3/4 or less we would not get a gas smell. We had the marina check all sources of potential gas leaks and after 7 seven years of ownership we never did find the source of the problem and we always tried to fill this boat less the full due to the gas smell issue.

When we sold the Prestancia for our current 328 Vista, we kept in touch with the buyers of the Prestancia. I can't remember the reason why the new owners found the source of the gas smell when the tanks were full, but it was that a screw that was used was up close and touching up high on one of the fuel tanks and this screw had caused a very small hole that gas was able to seep through when the tanks were full. Go figure eh?

Mike.
Author:  LouC [ Tue Dec 23, 2014 2:44 pm ]
Post subject:  Re: Raw Gas Smell
I forgot to mention this earlier, it is actually possible for fuel vapors to leak through the sending unit itself, there is a fitting with a nut on it that can be a bit loose. Another thing to check.

http://www.overtons.com/modperl/product ... gi?i=74917

see the nut in the center if you scroll over it to make the pic larger? Make sure its not loose. Do not overtighten though....
Author:  Bliss36 [ Sun Jan 25, 2015 4:50 pm ]
Post subject:  Re: Raw Gas Smell
Well I finally got around to making a pressure test fitting for the fuel tank and had a friend help me test the tank/fittings yesterday. The good news is the tank, fittings, and sending unit show no signs of leakage. We pressurized the tank to 20 psi and soaked everything with soapy water and not a single bubble showed.

So basically I'm back to square one with my search and at this point I'll need to have it back in the water to try and re create conditions. I'm starting to wonder if my blower going bad had anything to do with the sudden increase in fumes, but I would assume I shouldn't smell raw gas anytime. Looking at the way the 268 is setup if there are any fumes they would probably collect under the mid berth. The fuel tank is mostly under the mid cabin but a little bit pokes into the engine compartment without a seal to prevent fumes from going under the mid berth. Maybe I should use some expanding foam to seal these gaps and see if that isolates the fumes to the engine compartment only. Any thought or idea's?
Author:  alex8q4 [ Sun Jan 25, 2015 5:11 pm ]
Post subject:  Re: Raw Gas Smell
You have not commented on the condition of your vent line. I am sure you have looked at the tank side as you would have had to plug it to do your pressure test.
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