Smell gas in cockpit with full throttle in level flight. Normal?

[Roger Lee]

If you think it's coming from under that crush washer on the fuel in hose connection just try tightening it down more as a start. It mat fix it or may not. Then you could try new crush washers, but usually crush washers just don't up and go bad unless someone has messed with thm.

[gogogo888]

More updates:

There is no fuel streaks behind the sign tubes nor on the wing roots/under the wings.

The floats after drying for an hour weights 6.3 grams.

There are fuel streaks between the bowl and the carb under the fuel line as shown in pictures above.

Will try to tighten the fuel line crush washer.

[Tom Baker]

A couple other things to check would be the fuel valve behind the panel. I know of a couple that started leaking over the past couple years. Another thing would be to check the hose for the fuel pump drain. It would be possible to have a failing pump have a little fuel come out of the drain. Neither of these should be regulated to full throttle flight though.

[Tip]

I have had issues when reusing the cork bowl gaskets. They tend to not stay in place when replacing the bowl which leads to a leak.

[gogogo888]

14 minutes ago, Tip said:

I have had issues when reusing the cork bowl gaskets. They tend to not stay in place when replacing the bowl which leads to a leak.

Good to know, I will just replace the gasket.

[gogogo888]

22 minutes ago, Tom Baker said:

A couple other things to check would be the fuel valve behind the panel. I know of a couple that started leaking over the past couple years. Another thing would be to check the hose for the fuel pump drain. It would be possible to have a failing pump have a little fuel come out of the drain. Neither of these should be regulated to full throttle flight though.

Thanks Tom. Will do.

[FlyingMonkey]

13 hours ago, gogogo888 said:

Good to know, I will just replace the gasket.

I have had problems with the bowl gaskets leaking in the past.  It was a combination of gasket issues and heavy floats, it took a while to fully sort out.  The newer black rubber/viton gaskets seems to be a little better than the green fiber gaskets, so swapping those out if you still have the green ones (or the ancient cork ones) is a good idea.

As a last resort, if you can't get a good seal on the bowls you can lap the bowl rim to make it more perfectly flat.  Lockwood walked me through the process and it's not hard.  If you have continued issues PM me and I'll tell you how.

It does look like your primary issue is at the fitting; I'd get that sorted first.   If you clean it off well and tighten it down, and still have issues, new bowl gaskets might help.  Just remember if you see fuel stains like your picture shows between the bottom of the fitting and above the bowl, you have not solved the fitting leak.

I'm still surprised if this is your only issue that you can smell fuel in flight.  I had a bad leak when a carb bowl pin worked lose that was literally pouring fuel on the ground under the cowl, and I didn't smell it until I stopped the airplane and opened the door.  If you haven't done it yet you might consider pulling the panel and inspecting the filter and fuel lines behind the panel for leaks as well, just to make sure this is your only problem.

[gogogo888]

So, I replaced the gasket and got a really good seal.
After a 4,000 RPM run up my left carburetor is dripping like this. Right carburetor is completely dry.

Normal?

 

 

[FlyingMonkey]

Dripping fuel from the carb is never normal.

[gogogo888]

3 minutes ago, FlyingMonkey said:

Dripping fuel from the carb is never normal.

Any idea how to fix it?

[Tom Baker]

You either accidently let the gasket get out of place, or the floats are hung up keeping the float needle from seating. I would drop the bowl again. Look at the gasket to make sure it is in place. Work the float lever up and down a little. Put it back together and check it again.

[DHeal]

Yikes!  Fuel dripping from the carbs is not good.  Do both carbs drip or just one side?*  Some troubleshooting thoughts:  1) Poor bowl gasket and/or poor bowl gasket seal -- IMHO the original cork gaskets are lousy -- I have had great success with the green composite gaskets;  2) Worn float needle valve and/or needle valve orifice -- see Rotax manual for test procedure in this regard;  3) Excessive fuel pump pressure is overpowering float needle valve assembly -- see Rotax manual for test procedure in this regard.  My money is on #1.

*If only one carb is dripping it is likely a problem with that one carb.  If both carbs are dripping it could be a system problem -- excessive fuel pressure??

[gogogo888]

It was the gasket that was not in place properly. It was pretty tricky to put it in. I took the bowl out, double checked the floats and then made sure the gasket went in properly.

Then I test flown the plane for 30 min with various RPMs, no more gas smell and the carbs are dry!

Thank you all for your help!

[FlyingMonkey]

Glad it's sorted out...keep an eye (and nose) on it for the next few hours of operation.  I'd pull the cowl and check it before and after the next three flights at least.