Gasoline smell

[High Hopes]

Hello All,

It's nice to be back, except not so good to have a problem. My A4 purrs away beautifully. There may be a prop size / max rpm / barnacle issue, but the real problem is a gasoline smell.

When the engine is running, there is no gas smell. The engine warms up, the blower runs, the engine compartment gets dry, and all is well. But when I return to the boat and open the hatch, the stale gasoline smell is awful. I think this smell was less noticeable when the engine was out of the boat, but I can't remember for sure. The tank was near empty at the time.

The odor seems to be strongest in the compartment where the fuel tank is located. I think the odor is coming from the top of the tank. The vent, fill, and gauge ports are on top of the tank.

The tank is aluminum. Could it have a crack and be leaking?

Also, is there such a thing as a gas detector for gasoline like the Freon sniffers HVAC techs use to find leaks. I can't get my snout to the top of the tank. There is no room for my head.

Any suggestions?

Steve

[tartansailboat]

gasoline smell

I have the same problem. Smell is there when the boat has been closed up and sat for several days. No odor when the engine is running or when the hatches are open. No smell when we sleep aboard even though the hatches are closed. I cannot find any gas tank leak but maybe the fill hose is porous or not well sealed. Have to take apart some of the interior trim to get at the top of the tank, my next job. Let me know if you find the source of your leak.

[dvd]

As far as I know my sense of smell is at least average and I can say that I don't think I have ever smelled gas on or about the engine. I think you need to check harder for any fuel leaks. You probably have a very small one some where.

DVD

[ArtJ]

Gas Fume sensor

I bought a gasoline fume detector with a gauge that mounts in the cockpit
firewall several years ago from West marine. I see that it is still for sale
on page 127 of their 2009 catalog. It is model M-1. The only problem
I have had over 7 or so years, is if the sensor became detached from
the underside of the cabin sole and gets dosed in water. That killed it
permanently and it was around $70 bucks or so for a new detector.

Other than that it has worked fine

[rigspelt]

I was convinced I could smell gas when we first put our refitted boat in the water last summer, when I opened up the boat. Everyone else looked in, sniffed and said I was overanxious. I put a paper towel under the carb I had rebuilt and finally found a slow drip, even with the fuel shutoff valve turned off. Replaced the carb with a new one: no leak, and no smell.

There is a thread here somewhere where a bunch of us shared similar tales of finding small gas leaks after carefully tracking down the odour. My new personal rule of thumb: if I can smell gas, there is gas leaking somewhere.

[Mark S]

My new personal rule of thumb: if I can smell gas, there is gas leaking somewhere.

Absolutely so.

Steve, last fall when we closed up Weetamoe on the jack stands I noticed a strong smell of gasoline when I came back to do some work. We were new to the boat then and the prior owner never shut the petcock, so I hadn't either. I shut the petcock for the first time that day and have never had the smell again. Ever since then I shut the petcock when the engine is off for the night. That's my story; yours may vary. But if you smell it, it's there, and an errant spark will find it.

Mark

[roadnsky]

When I first got my boat, I had the same issue.
Smell of gas in and around the tank AND I noticed it in the lazarette.
I changed the FUEL FILLER hose from the deck plate to the tank.
No more smell whatsoever.
(Neil, not as good as heretofore, but hey...)

Mark also has a good point to make sure you try.
(Make sure and close the petcock)

[CalebD]

I went through this fire drill recently when my co-owner started complaining about a gasoline smell in the cabin of our Tartan 27. I took our carburator off and cleaned it and kept oil rags under the carb. once I replaced it. There were stains on the rags from gas dripping out of the carb. Spoke to Don Moyer who said that the fuel pump will not stop gas from gravity flowing to the carb. Since then we have religiously turned off the gas petcock/valve and have much improved results. If you want to be really anal about it you should first shut off your main gas petcock/valve and run the engine until all the gas in the filter and lines burns up and the engine dies from fuel starvation. Not really a bad idea anyway as gas sitting in the carb will turn to varnish or drip out into my bilge. I cleaned and painted the bilge so I am more sensitive to keeping it clean now.
Sometimes I even run the engine for a few seconds with the raw water seacock closed to get a little extra water out of the system. Your mileage shall vary.

[High Hopes]

Thanks everybody. Good ideas.

Mark, I do keep the petcock closed although I don't always shut it off at the same time I turn the engine off. It is usually a leaving the boat activity. Sometimes I forget, but it doesn't seem to make a difference, smell-wise, when I return. The valve is as older than Methuselah, but it has a smooth stroke when it is turned and it doesn't seem to leak.

I am using a rubber fuel line from the tank. The original was copper, but I had this problem with the metal line as well.

Caleb, I have run the carburetor dry on two occasions and that didn't help. BTW, if you want to avoid varnish, do not run the bowl dry. Gas needs oxygen to cure. If the bowl is full, there is too much gasoline vapor to allow any curing to take place with the little bit of air that is available.

Rigsy, thanks for the suggestion about the rag under the carb.

Roadinsky and DVD, yes. I fear one day the little leak will become a big problem.

Art, thanks for the recommendation. I will get one of these when we start sleeping overnight. I was actually thinking of a portable unit with a wand to investigate with.

Tartan, I will keep you posted.

[67c&ccorv]

Steve, is your tank venting system secure - ie. no leakage anywhere and properly routed outside of the hull of the vessel?

[ndutton]

I have the Xintex MB-1 gasoline detector wired to activate the blower automatically if it senses combustible fumes of any sort. Even with that I still manually shut off the fuel supply when closing up the boat having experienced a carburetor drip a while ago. My shut off valve is just before the carb.
When employing your own personal olfactory system, get your proboscis right down in the bilge, that's where the heavier-than-air gasoline fumes will accumulate.

(There ya go, Jerry - double whammy)

[Administrator]

Steve:

I have a background in Emergency Services which admittedly colors this response, but perhaps it will help. Assuming you are served by a local volunteer fire company, they will likely have a "sniffer" used to track down and measure dangerous vapors. If you know one of the volunteers or know someone who does, ask about having them stop by (on a non-emergency basis) to see if they can find the source.

I emphasize non-emergency. If you are casual about that part, you may end up with two engines, a truck, a chief's command vehicle, an ambulance, a paramedic unit, and maybe a hazmat unit for good measure.

Bill

[sastanley]

fuel

Steve, I experienced this same phenomenon last spring. I traced it to a pinhole leak in the bottom corner of my fuel tank. Laying clean paper towels as suggested is a great way to source it. Gas smell is very pungent, if you smell it, it's there. Also, double check your clamps. I was surprised how loose my raw water intake line was to the water pump when winterizing last week.

Neil - is that one shut-off valve the only one you have? I have purchased a 2nd petcock, and I am trying to figure out the best place to put it. My goal is to make fuel shut-off more accessible & more convenient. My current shut off is at the top of the pick up tube on the tank..as you well know, on the C-30 that is not what I would call 'easily accessible' - With my new tank, mine is behind the bottom drawer of the aft galley drawer assembly. That is more convenient than emptying the quarter berth to lift the access board, but it is still a hassle.

For 'regular-every-day-leaving-the-boat-so-I-am-not-relying-on-the-carb-float' to hold all the fuel back, I want to add that second petcock. I have my Racor mounted in the engine compartment, and I was thinking about mounting the fuel shutoff to one side or the other of that...however, your shut off at the carb is interesting..there doesn't necessarily seem to be an issue with fuel in the Racor & fuel pump, the goal seems to keep from relying on the float valve in the carb.

Does that make sense?

[Dave Neptune]

Filler hose

Three years ago I over filled my fuel tank IE fuel up in the filler hose above the tank and noticed a smell I had not detected before when I went below. I checked the locker containing the fuel tank and it was leeaking through the hose below the clamp on the tank. I drained some fuel and replaced the hose which had completely degraded under the clamp. All better!!!

FYI Dave Neptune

[baileyem]

fuel leaks

I have found that a small, dental-style mirror and a good light source are invaluable when looking for a slow, weepy-type leak. You have to clean things up well, wipe and dry around suspected leak area and use the light and mirror to get ar really close look at the area. Even very slow weeps show up quite readily. A source of compressed air can be a big help in drying things out in hard to reach areas.

Keep looking. There is a leak somewhere.

Mike