L

lpeeds

Member
I am working on the PAP List and when I got to the fuel test I have fuel leaking from the left carburetor. It is running from the bottom but I cannot tell where it is coming from. Does anyone have an idea what I might be looking for before I dig in?
 
Carb bowl gasket?

lpeeds said:
I am working on the PAP List and when I got to the fuel test I have fuel leaking from the left carburetor. It is running from the bottom but I cannot tell where it is coming from. Does anyone have an idea what I might be looking for before I dig in?
Click to expand...

My first guess (using my infinite whiz-dumb) would be some kink in the carburator bowl gaskets. The stock versions are made of cork, and seem a bit delicate to me. After pulling the bowls off and re-installing, then pulling them off again, I had some (not quite leaking yet) damage to one of them. I put some neoprene version in place of the cork versions.
 
It could be a number of causes... you need to determine where the fuel is leaking from.
Is it from the vent tube on the inboard side of the carb, or around the float bowl?
If the vent tube, then you probably have some contamination particles preventing the float needle from sealing in the seat (fairly common with a new build - stuff getting flushed out of the fuel lines, etc.).
 
Fuel leak from carburetor-Update

Thanks for all the suggestions. I also called Lockwood Aviation. I did find that the fuel was coming from the vent tube and Kerry at Lockwood suggested that it was probably some trash under the needle and that I should remove the bowl and floats, run some fuel through the carb while jiggling the valve. I did this and did not find any trash but the problem stopped. Thanks again.
 
lpeeds said:
Thanks for all the suggestions. I also called Lockwood Aviation. I did find that the fuel was coming from the vent tube and Kerry at Lockwood suggested that it was probably some trash under the needle and that I should remove the bowl and floats, run some fuel through the carb while jiggling the valve. I did this and did not find any trash but the problem stopped. Thanks again.
Click to expand...

Glad you (maybe) resolved it. Keep in mind that a large percentage of engine performance problems are caused by contamination in one or both carbs.
Sometimes it even moves around, such the the problem goes away, only to return later. Something to keep in mind as you begin your flight testing.
 
Carb bowl gaskets are the #1 offender by a huge margin followed by fuel out the vent with some debris under the needle valve. If you don't see fuel coming out the vent tube replace the carb bowl gasket. I always keep 10 or so gaskets around the shop because it is fairly common.
 
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