A Drip Of Fuel

While I was checking the oil this morning, I noticed a drip of fuel at the end of the clear plastic carb overflow tube. Never noticed that before. On initial climb out, I have noticed a slight fuel odor. It's short lived, but I am beginning to think that I may have a carb issue. Any thoughts??

Tom

recent experience here! Just had the same problem but much worse.
Trouble shooting advice from others had me pull the bowl and check for debris then flush some fuel through with a short (few second) run of the fuel pump and a rag to collect the fuel and see what happens.
That didn't help for me and it turned out to be a bad float, one was sunk in the bowl and the other was floating. That with a minor float arm adjustment and resync of the carbs all is well.

Mine was leaking much more fuel than you describe and the smell was quite prominent and somewhat disturbing!

Since mine is a SLSA I had a LSRM/Rotax guy fix it for me.

I think its a fairly common problem.

Common fuel leaks from the carb come from these areas:

Carb bowl gasket leaks (common)

float in bowl sinking (just had an RV12 with 68 hrs. with a sinking float and metal float arms out of adjustment)

Metal float arms out of adjustment. (not real common) 9Must remove carb and turn upside down to adjust and measure)

bad needle valve (not real common)

Thanks for the tips. It sounds like a little carb work is in order, and with just 61 hrs on the clock.............Tom

When flying at high pitch angles, practicing stalls, or even on climbout, would it be reasonable to expect some overflow out of the carbs? Not a steady stream or anything but a drop or two?

I just got another email an hour ago. Another RV12 with a carb leak for this next week. Must be the weather. LOL

KALEWIS said:

When flying at high pitch angles, practicing stalls, or even on climbout, would it be reasonable to expect some overflow out of the carbs? Not a steady stream or anything but a drop or two?

Click to expand...

Not sure, but you are correct in that the only time that I get the odor is during climb out. Never on the ground, and never during level flight, or descent. Also, the seep out of the overflow tube is just a drop or two, with only a spot of evidence on the little carb pan.

Tom

probably doesn't apply to a 12 but fwiw. i have a bing that would leak from the overflow. tried everything . checked floats, replaced floats, new needle, pulled needle seat from carb and put new one in. seemed to come and go. finally, i turn off my fuel valve off 10 seconds before i get back to the hangar. never leaks a drop in the hangar now. most likely this is because it is in a tail dragger.

Well, maybe another one. Now at 110 hours, I noticed that my passenger-side EGT has been lower than the pilot side. And I saw a drop of fuel on the end of the overflow tube, looking through the oil door after shutdown, on the passenger-side carb.

SO I went to ROTAX-owner.com and watched videos on the carb disassembly and reassembly. The reassembly video BRIEFLY shows the floats and their brackets and points out the need for symmetry of the bracket arms and paralleling of the bracket arms to the carb body, and making slight bending adjustments for that.

BUT there is no video about this specific "partial inspection" and I would REALLY appreciate a detailed description before I try it!

It seems that this can be done by:
Taking off the air filter.
NOT disconnecting any of the cables to the carb thus perhaps not needing rebalance.
Taking off the carb via the hose clamp.
Then what? Drop the bowl right side up? Or flip it first?
A full detailed description of the entire procedure would be most appreciated! Roger?????!!!!

Should I also suggest that to ROTAX-Owner as a potential new video?

THANKS!

Hi Bill,

Give me a call and I'll talk you through it.

Bill_H said:

It seems that this can be done by:
Taking off the air filter.
NOT disconnecting any of the cables to the carb thus perhaps not needing rebalance.
Taking off the carb via the hose clamp.
Then what? Drop the bowl right side up? Or flip it first?

Click to expand...

This was the method I used, and I ended up chasing a stuck float for more than a week. From a statistically insignificant sample set of one, I reached the conclusion that it is best to leave the carb upright when removing the float bowl.

i have popped my float bowl off my carb at least 10-20 times while mounted on the engine. definitely the way to go if you have got room. once in a while i didn't get the bowl lined up and it leaked, no big deal, take off the clip and remount the bowl.