I smell gas

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Grady208CT

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I am the new owner of of 2001 Grady 208 with a 200 Yamaha. Love the boat. However, the last two times I have topped off the tank I smell gas for long periods afterwards. The catch is I only smell fuel while running the boat. There is zero gas in bilge, engine is very clean and I don't smell gas while idleing at dock. Only when I move the boat do I smell gas. It smells raw and the fumes seem to be concentrated at the helm. I checked the tank, fuel lines, fuel filter, and stuck my nose in all access holes, nothing. If anything the smell is most pronounced stading up at the helm. At first I thought it was exhast collecting under the bimini but it's too strong to be that.

Does anyone have any suggestions?
 
Does this only happen when the tank is full? Perhaps once you are under way the fuel in the tank starts sloshing and is escaping through the vent. I am not familiar w/ the 208, I run a 265, but on my last boat, there was a vent on the side that allowed for venting of the tank and would sometimes spew fuel when the tank was full. Does the smell abate as the tank is run down? Maybe leaving the tank slightly less than full will help. It could be just the flow of air around the boat that draws the smell to the helm.
 
Hello Lefty,

Thanks for the reply. I was thinking the same thing. The smell does dissapate but I have only topped off twice and didn't think it was that pronounced the first time. I topped off the other day and went out when it was pretty snotty and got bounced around. That was when I really noticed the smell. I just came from the boat and ran the motor at the dock for about 10 minutes and checked all connections, hoses, etc and not a drip anywhere. What I find strange is that the tank breather line ties back into the fuel fill line just under the gunwale. If the tank is full and the temperature rises which will lead to expansion where does the expansion go? It's a closed system unless I am missing something. What I am thinking is that the gas is blowing past a seal somewhere and I am just missing it.
 
Grady208CT said:
Hello Lefty,

Thanks for the reply. I was thinking the same thing. The smell does dissapate but I have only topped off twice and didn't think it was that pronounced the first time. I topped off the other day and went out when it was pretty snotty and got bounced around. That was when I really noticed the smell. I just came from the boat and ran the motor at the dock for about 10 minutes and checked all connections, hoses, etc and not a drip anywhere. What I find strange is that the tank breather line ties back into the fuel fill line just under the gunwale. If the tank is full and the temperature rises which will lead to expansion where does the expansion go? It's a closed system unless I am missing something. What I am thinking is that the gas is blowing past a seal somewhere and I am just missing it.
Click to expand...

Your system is not closed. The gas cap has a vent hole to let air in. There is a little rubber valve on it and you may just be smelling gas that has leaked through the vent. On the other hand you could have a leak in the vent hose. Fuel isn't normally in that hose but can get there two ways: by sloshing out of the tank or by overflowing from the fill through the filler cap and into the vent. In either case, either the vent hose is leaky or the filler cap is leaking. Some vapor coming out of the cap is normal.
My advice is to check the vent hose and connections and not to fill the tank to the top.(always good advice)
Oh, check the cap also. That little rubber flapper valve should stop liquid fuel from leaking and usually stops vapot too.
 
I hope you and your crew don't smoke.

Have you accessed the vent and fill line connections at top of tank to inspect them? A big hose and litle hose together? Rub finger and smell it.

Did you inspect the level sender for signs of wetness or leaks, check screws?
touch it with finger and smell it.

Next to level sender is feed line to motor, is the fitting tight and clamp tight?
Finger smell test.

Clamps tight?

There' no topping off marine fuel tank, stop that.

If you need more gas carry 6 gallon poly portable gas tanks.

Does gas come out of fill/vent combo fitting on gunnel or wherever it is ??
Put your nose there, what do you smell? If you smell gas on brdige and the same time you take your nose to the port and no smell, it is someehere else.

If your finger smeall of gas anywhere, it is leaking.
If all above is good, and unless when you step up on bridge deck and the tank top is not being weighted even a bit to push out vapor, then you have a hole in top of tank. Check first areas under black neoprene strips.

Not likely hose leak at this age of boat.
 
Thanks Bob P.

I think the problem is my topping off. I checked everthing again today and no drips. When I opened access plate and stuck my nose as close to tank fittings as I could the gas smell is nominal if anything. You know you are smelling a gas tank but it is really more of a grimy smell than anything.

I will do the touch test on all fittings and then sleep well.

Stupid question (but here goes anyway): When I fill up, I turn off all electonics and kill the batteries so there is no chance of spark, but my gas gauge is electronic. Outside of hearing the gas gurgle as it comes up the fill line, how do you guys know when you are reasonably short of topping off? Do you count gallons?
 
If you know you have a hundred gallon tank...you don't put hundred and two gallons in it...which is to say YES you count gallons...but in this age of crappy gas we tell people to only get what you are going to burn in the next month...you know how much you'll need to get out and back...just get that much plus a little more.
 
I'm not familiar with your model, but I had a similar issue which turned out to be a leaking tank. Yours being a 2001 sounds a little early to be having tank problems. But, the tank compartment is sealed off from the bilge (to contain any leaks and keep it out of the bilge). On mine (1987 Overnighter), there is a drain plug accessable through the transom deck plate (full arms reach back towards the front of the boat while laying down on the transom). After smelling fuel on a couple trips, while looking into it I discovered this plug. When I pulled it, I caught several gallons of fuel that flowed out of the tank compartment, through the bilge & out the drain. Something you may want to check.
 
Grady208CT said:
Thanks Bob P.

I think the problem is my topping off. I checked everthing again today and no drips. When I opened access plate and stuck my nose as close to tank fittings as I could the gas smell is nominal if anything. You know you are smelling a gas tank but it is really more of a grimy smell than anything.

I will do the touch test on all fittings and then sleep well.

Stupid question (but here goes anyway): When I fill up, I turn off all electonics and kill the batteries so there is no chance of spark, but my gas gauge is electronic. Outside of hearing the gas gurgle as it comes up the fill line, how do you guys know when you are reasonably short of topping off? Do you count gallons?
Click to expand...
That's a good question. It's tough to 'fill' up without overfilling. It is possible to estimate the amount of fuel that you will take and before you get to that amount, slow the fill and listen. You should be able to hear that point when the fuel hose start to fill and stop there. I don't think that I can estimate my fuel level to better than within 15 gallons of the 208's 80 gallon capacity. For what its worth, the Yami gauge blinks the lower bar as a low fuel warning. That happens with about 20 gallons still in the tank ( 1/4 full!)
If I add 10 gal of fuel, on average the gauge will display 1 additional bar when I stand at the helm. Note that this is not an exact science and is based om my boat, fuel sender , gear, etc.
Make sure everybody is out of the vessel.


With regard to shutting all electronics and the batteries, I know that is the usual approach for inboards but here is my problem with that practice. There is no bilge ventilator and therefore a much higher probability that a spark will be generated when you switch the batteries on. If there are fumes, an explosion is more likely.
So I open the rear battery covers , let the bilge air out and smell around before switching the batteries on.
Opening the fuel tank access cover every now and then and taking a good sniff is a good practice also
 
You've gotten great suggestions on fixing your problems from the forum. I would just add that being you tend to top off your tank, there is a strong possibility that you are getting raw gas into your vent hose now and then. Although the boat isnt that old, sometimes these hoses get a little porous with age and can let some odor escape. Generally with a raw gas leak you can definitely smell it and its usually all the time. I would look at the vent/ vent hose/ vent connections area first. Just a tiny cut near where the clamps are attached and the hose flexing there can be enough to cause the odor you are smelling. Good luck.
 
I had a very similar issue last spring on my '86 Sailfish. Freshwater boat, but had just replaced vent, fill and engine lines as well as taken out the Fuel level sending unit a few times to try to get it working again. No evidence of fuel in the bilge just fumes backing up into cockpit and cabin after fillup and shortly afterward. Turns out I had a bad seal on the sending unit, replaced it and end of problem...
 
Thanks for all the GREAT responses. This is a terrific forum. I will check out all suggestions and post what I find.
 
You can get a Flowscan or Yamaha Fuel Management gauge, or similar device - it has a totalizer that counts how many gallons used, among other things.

It's very accurate, so when you actually fill next time, you can reset it and refill based on same amount used, so if you used up 50 gallons, then add 50 gallons.

The gas gauge is useless for such accuracy.
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I'll get a spell checker.
 
Went out again Saturday. No gas fumes. Tank was around 3/4 full and I burned down to below 1/2. Got bounced pretty hard and still no fumes. I did finger test, checked all connections, and even yanked cover off of fresh water tank compartment just to make sure. No problems anywhere. Pretty confident my issue was topping off.

Thanks for all the great replies. Lesson learned on my end.
 
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