Gas back up???

I have a 2011 Lund Impact with 115 meet 4stroke. I’ve never had problems but today I was looking it over and noticed the air filter is completely disintegrated. I looked online and its a common problem, I’ll just need up get a new filter. Merc re-designed them so it’s not supposed to do that anymore.

So, while checking this out, I removed the filter and left the hood off. A little time later I noticed I was smelling gasoline and couldn’t figure out where it was coming from. I was smelling it in my garage and not by the motor so I thought one of my kids knocked over a gas can or something. Finally I noticed gas was slowly dripping off the side from where you fill up. I opened the gas cap and got sprayed with gas (SUCKED!).

After cleaning up I liked again and it seemed fine. I started motor and everything ok. I put the air filter back on and kept looking. I opened the gas again and noticed it was “burping”.

About 20 minutes passes and I’m looking again and its leaking. I CAREFULLY opened the cap again and it spews gas.

WTF??? Does anyone know why in the world this is happening? I am stumped.

Thanks!

Possibly the tank was filled in cold weather and now was expanding with warmer weather?

Luckydave, I think your right. After putting the post up I kept checking and thinking what it could be. The last time out I filled it and ended up filling it completely full, which I usually don’t. I didn’t run the big motor much and it was about 40°. Now its nearly 70°. I think I’ll try and siphon out some and see if that helps.

I will go off luckydave’s idea. Look for blockage into air intake for the gas tank.
Story time I had a hard time starting a cutoff saw on a hot day of hard use. I checked the fuel and fuel errupted like a volcano out of the fill spout.

ClownColor wrote:

But…liquids don’t compress,or is my 9th grade science all wrong?

plastics and even metal expand under pressure. Gas tanks made out of a form of plastic or a thin metal.

I would look for a vent that is not working properly. Sometimes it can air lock your motor too. Just like if you where running a boat that has a removable gas tank. if you don’t open the vent it run but will motor will die when it doesn’t siphon from the gas tank. I don’t know if I explained it very well.

I believe the tank vent has had a paper wasp (or an insect of the like) fill your vent tube. I would think if you were out on the lake with the fill cap on tightly it would also not run very well after a while like it was starving for fuel. Why else would it build pressure unless it could not vent?

On the subject of your air filter. I had the exact same thing happen on a 2010 Mercury 115 4 stroke, all of the foam was completely gone so all that was left was the plastic cage the foam was attached to. The new replacement filters do not have any foam and will cost you about $80. Funny thing is that there was very little foam in the engine compartment. Hmmm, where did it go then?
Lots of info on this issue if you search “mercury 115 four stroke air filter problems”.

Does anyone know where the vent is for the gas on the 2011 impacts?

case1803 wrote:

Does anyone know where the vent is for the gas on the 2011 impacts?

Do you have good sight of your tank? there is usually a tube Y’d off your filler hose or the filler cap itself is vented

ClownColor wrote:

But…liquids don’t compress,or is my 9th grade science all wrong?

You are correct. They do not compress, but they do expand and contract with temperature change.

Bill nye the science guy confirms with a beaker of water and a burner

One concern with global warming isn’t the melting bergs raising the water table (i.e. introduction of more water), it is that the rising temps will expand the existing water table.

Back to the boat… Does seem feasible that a vent is blocked.