fuel from carb

[prkaye]

I was working my throttle arm back and forth a bit this morning, working on getting the cable reach set properly. I noticed some fuel dripping from the air filter bypass door at the bottom of my FAB. Is this something to be concerned about??

 

[CATPart]

the carb has a small pump on it that squirts some fuel when you pump the throttle, which normally you do with the engine turning, so it gets sucked in instead of dripping out. this is likely what you are observing.

 

[Roadjunkie1]

"Accelerator" pump....

the carb has a small pump on it that squirts some fuel when you pump the throttle, which normally you do with the engine turning, so it gets sucked in instead of dripping out. this is likely what you are observing.

Exactly what you observed. It is an "accelerator" pump that squirts a quantity of fuel into the throat of the carburetor when you advance the throttle. If you look at the port side of the carburetor, (opposite the throttle linkage) it has a small chrome shaft sticking out of it, linked to the throttle linkage by the same shaft that runs the butterfly valve inside the carburetor. It will move down when the throttle is advanced and up when retarded (pump, refill). Some pilots have no primer and use this to prime the engine when starting...while the engine is turning! Unless you want to see what a FAB fire looks like.

 

[Ironflight]

Exactly what you observed. It is an "accelerator" pump that squirts a quantity of fuel into the throat of the carburetor when you advance the throttle. If you look at the port side of the carburetor, (opposite the throttle linkage) it has a small chrome shaft sticking out of it, linked to the throttle linkage by the same shaft that runs the butterfly valve inside the carburetor. It will move down when the throttle is advanced and up when retarded (pump, refill). Some pilots have no primer and use this to prime the engine when starting.

I took a video of this once with a carb sitting on the workbench - the stream of fuel went about six feet straight up into the air from the throat of the carb. efficient little pump…..

https://youtube.com/shorts/SWEe1oRFyC8?feature=share

Paul

 

[RV8JD]

I took a video of this once with a carb sitting on the workbench - the stream of fuel went about six feet straight up into the air from the throat of the carb. efficient little pump….. (wish I could find the video….)

In one of your many excellent KitPlanes articles:

https://www.kitplanes.com/priming-with-the-pump/​