New carb runs too rich.
Hello VAF brain trust. I have an O-320 powered RV-4 that has what appears to be a fuel-related problem, but I cannot for the life of me understand what's going on.
My engine started running rough a few months ago. In my attempts to find the source of the problem I've changed out the carburetor, the mechanical fuel pump, the plugs, and the harness, with brand-new or 0-time overhauled parts. It still wont run right!
The engine starts up OK, but as the throttle is advanced it loads up with excess fuel, running rough and very rich, pumping black smoke out the exhaust. The engine will not even shut down with the mixture at idle cutoff - it simply continues to run, idling away.
After shutdown (via the mags), fuel drips out of the carburetor throat (note this fuel is not coming out of the carburetor overflow vent, but the carburetor throat itself!). I've checked the float level with the carburetor on the aircraft many times - it always settles exactly where it should.
Reading VAF forums, I though it might be related to the mechanical pump, possibly over-pressurizing the carburetor. So I by-passed the mechanical pump and ran the engine on the electric boost pump. No change.
I'm at my wits end trying figure this out. The only thing I haven't changed out are the mags. Mags only have about 300 hours. Could faulty mags somehow cause this? Should I purchase ANOTHER new carburetor? What else can I look at?
Myself, and everyone else at my airport are stumped.
Thanks in advance for any suggestions..
Hello VAF brain trust. I have an O-320 powered RV-4 that has what appears to be a fuel-related problem, but I cannot for the life of me understand what's going on.
My engine started running rough a few months ago. In my attempts to find the source of the problem I've changed out the carburetor, the mechanical fuel pump, the plugs, and the harness, with brand-new or 0-time overhauled parts. It still wont run right!
The engine starts up OK, but as the throttle is advanced it loads up with excess fuel, running rough and very rich, pumping black smoke out the exhaust. The engine will not even shut down with the mixture at idle cutoff - it simply continues to run, idling away.
After shutdown (via the mags), fuel drips out of the carburetor throat (note this fuel is not coming out of the carburetor overflow vent, but the carburetor throat itself!). I've checked the float level with the carburetor on the aircraft many times - it always settles exactly where it should.
Reading VAF forums, I though it might be related to the mechanical pump, possibly over-pressurizing the carburetor. So I by-passed the mechanical pump and ran the engine on the electric boost pump. No change.
I'm at my wits end trying figure this out. The only thing I haven't changed out are the mags. Mags only have about 300 hours. Could faulty mags somehow cause this? Should I purchase ANOTHER new carburetor? What else can I look at?
Myself, and everyone else at my airport are stumped.
Thanks in advance for any suggestions..
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