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Fuel smell in the air cleaner

Roger Lee

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Posted on another forum, but a good question.



fuel in the air filter

Two or three time I forgot to switch off the fuel selector any my fuel tank would enpty on the floor through the air filter dripping alongside the firewall. That started when I took delivery of the plane in 2007 and has never stopped. Carb inspection by rotax did not show anything wrong. Each time I fly I got that fuel semll in the cabin for a long time. I could not figure out yet if the same leak occurs while flying or only on the ground when I forget to shut of the fuel valve.



The fuel smell is coming from the air cleaner via the carb vent tubes. This is being caused because the fuel wasn't turned off, but more importantly the fuel is leaking by the carb needle that is controlled by the floats and as the floats rise the needle should shut the fuel off. This is what controls the fuel flow when we fly. When he is in cruise the fuel is all being used so no over flow to the vents. If the float arms are out of adjustment then leaving the fuel on will cause the carbs to over flow because the fuel never fully shuts off. Then it goes out the vent tubes that go into the air cleaner. So not only could you get a fuel smell, but you could get fuel on the ground. There is a small amount of head pressure since our fuel is a lot higher than the engine. The fix is two fold.
First the carb float arms need adjustment and two the fuel in our CT's should turned off when not in use.
I learned a long time ago with Honda engines that fuel will leak past carbs and rings at times and get into the oil. Too long a post to say when and how, but it can and will.



If someone sees the gentleman on another forum you might tell him where to get his answer.


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Howdy Ranger,


From time to time I see post from other places that I think would be good info for our members here. On the forum that this came from I can not post and was removed as a member. Nothing I can do about that, but I can make sure you guys here get all the info possible so you can be well informed and be prepared for what ever comes down the road. Sometimes I read an article, see a post or come across something during maint that I think someone might get something they can use someday. My focus is to help all those I can and hope the others that I can't will come take a look. You can help others too by letting them know, no matter were they may be lurking, that we have a fun and informative place and to come join us. I believe everyone on our forum has good a good knowledge base with everyone's experience and we are fun group. I do post on 4-5 other forums so maybe this person might see it. I will say this forum is my first Love so you guys are number 1 in my book.

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