Heat and Fuel Expansion

[seedlings]

New to boats and boating, and have another question.

I filled my 6gal tank with fuel/oil mix a couple of days ago to get this motor started for the first time in 20 years. I did get it up and running, which is great, but after I ran it for a little bit, I pulled the fuel lines and tarped the boat back up. Boat is outside right now.

Next day, I went to replace the broken bilge pump and the gasoline smell was intense. I pulled the tank out and set it under the boat while I worked during the afternoon. I climbed down off the boat and the fuel was seeping out of the small tube where the fuel line connects to the tank (fuel line was not connected).

Should I not put 6 gallons in a 6 gallon tank, or is there something I'm overlooking regarding the fuel expansion? I don't want to get out on the water for the first time and have gasoline seeping out everwhere!

Thanks,
CHAD

 

[Phantom_II]

Re: Heat and Fuel Expansion

If you pump fuel from a nice, cool underground holding tank into a small, solar heated gas tank, you will get some expansion.
Next time, just leave a little bit of expansion room in the tank. There's no real need to fill it to the brim.

 

[seedlings]

Re: Heat and Fuel Expansion

Thanks for the reply.

I may just "burp" the gascap every so often after filling until the temp stabilizes.

CHAD

 

[Ned L]

Re: Heat and Fuel Expansion

I would suggest there is more going on here. The fuel fitting on the top of the tank has a spring loaded valve in it which is supposed to shut the fuel off when the fuel line is disconneced. It sounds like yours is leakig & needs to be fixed//repaired.
Just 'burping' the cap probably won't work. Once the temperature of the gas is equalized and you 'burp' the cap, the gas (& ethanol) inside the tank will want to evaporate into the air space inside the tank, and in doing so will build up a bit of pressure. This pressure will force the gas up the fuel line and out the leaking fitting. - If you have one of those 5 gal plastic unvented portable gas cans at home you have probably noticed that every time you take the cap off it 'hisses' a bit in warm weather.
For the short term you might leave the cap loose to vent the tank. This will cure the gas coming out of the fitting, watch out for the gas fumes though. A better idea would be to leave the fuel line connected to the tank & disconnect it from the outboard.

 

[seedlings]

Re: Heat and Fuel Expansion

A better idea would be to leave the fuel line connected to the tank & disconnect it from the outboard.

Done. Thanks.

CHAD