Slight gasoline smell in winterized boat

[amizerin]

I winterized my boat a month ago because of Dorian. Gasoline smell has never been an issue in the season. Yesterday, I went down to the companion space to check something and smelled gasoline a little bit. The gas tank was topped up (which almost never the case in the season) and fuel line was shut off a month ago when I winterized the boat.
I checked everything I could reach to and did not find any leaks. I smelled the bilge and all around the engine and it seemed fine. The fuel level seemed the same as a month ago from what I can tell. Wondering if it could be some evaporation from carb. Any thoughts?

[zellerj]

Old aluminum gas tanks can develop pin hole leaks from corrosion with water that settles at the bottom of the tank. Usually one side of the tank is a little lower than the other. I would find the low side of the gas tank and check for corrosion. A small leak in the gas tank would lead to an odor, but would not be perceptible on the fuel gauge.

I never smell gas so I doubt if it is evaporation from the carb.

[Administrator]

Do you have a mechanical fuel pump?

Bill

[amizerin]

Do you have a mechanical fuel pump?

Bill

Yes, it's mechanical.

[Al Schober]

Check the hose between the deck fill and the tank. I wanted to remove my tank to check for a leak, and the hose crumbled in my hand when I tried to remove it.

[Administrator]

Yes, it's mechanical.

Check the smell of the oil.

Bill

[capnward]

Also, take off the oil fill cap and sniff the crankcase. And make sure gas isn't dripping from the bottom of the carburetor.

[Bratina]

My mechanical fuel pump leaked very slightly at the top of the sediment bowl, where the cork gasket had degraded. Additionally the upper housing had bowed a little, meaning a new gasket reduced, but never entirely removed, a slight gas smell.

The solution was to replace the mechanical pump with an electrical kit. The boat smells significantly better.

Kit was very easy to install - one of my favourite engine upgrades.

https://moyermarine.com/product/engine-mounted-electric-fuel-pump-kit-fpmp_10_52/

[amizerin]

My mechanical fuel pump leaked very slightly at the top of the sediment bowl, where the cork gasket had degraded. Additionally the upper housing had bowed a little, meaning a new gasket reduced, but never entirely removed, a slight gas smell.

The solution was to replace the mechanical pump with an electrical kit. The boat smells significantly better.

Kit was very easy to install - one of my favourite engine upgrades.

https://moyermarine.com/product/engi...it-fpmp_10_52/

Are there any other advantages of the electrical pump vs mechanical? I was thinking to upgrade. Will it make cold start better? My engine starts on the 5-th sometime 6th turn of the ignition key after long periods of not working (e.g. a week). After I start and let it work for a little bit it starts just fine all day.

[capnward]

yet more mechanical pump advocacy

If my mechanical pump developed a bow in the upper housing I would replace the upper housing with the stiffer improved version, if Moyer wasn't sold out of them. https://moyermarine.com/product/uppe...fpmp_12-1_356/
I prefer a mechanical pump for several reasons. The main reason is the hand bail that enables me to prime and pressurize the fuel line before starting. This makes it start right up, without having to crank several times to draw fuel from the tank. No electricity involved. No need for an OPSS to be bypassed to prime the fuel system. In April this year it started in the first few seconds of cranking after 5 months off. Also mechanical pumps have more suction, and are more able to overcome small air leaks. I rebuilt mine about 20 years and 2500 hours ago. I put the rubber(?) washer at the top of the sediment bowl and fixed the leak. IMO, electric pumps are not an upgrade over a working mechanical one, but I realize the consensus is they are. They are definitely easier to replace, which is good because trying to fix them isn't worth it. I believe that mechanical pumps need non-ethanol fuel with MMO added so that the washers, seals and diaphragm aren't degraded.
Luckily for me, my upper housing shows no signs of bending after 20 years. It doesn't leak at the sediment bowl. The only time I smell gas is after priming the fuel line until the float valve closes. Then if I kept pumping (which I don't), I might smell a little bit wafting through the flame arrestor. Because I then start the engine immediately, vapor goes back into the carb, no more fuel vapor comes out, and the scavenge tube draws any gas at the bottom of the carb into the intake manifold. If I was worried about too much gas smell, you bet I would be running the blower for several minutes before starting.

[Dave Neptune]

On a boat the only place I want a spark near my fuel is in the combustion chamber!
As long as the mech pump is repairable I'd do it.

RE the seal I remember a member cutting off the "bowl assembly and tapping direct into the pump. I saved one to do that with but the occasion never arose. Rebuilt once in 34 years!

Dave Neptune

[ndutton]

From earlier this year:

http://www.moyermarineforum.com/forums/showthread.php?p=118068