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Fuel Draining from FAB

Inhot

Well Known Member
Patron
Hi guys,
O 320 D1A. To sample from my gascolator during preflight I need to have the fuel pump energized. Yesterday when doing this I took longer than normal after energizing the pump before getting back out to the engine (about 60 secs, couldn't find the fuel sampler). I observed fuel dripping from the bottom of the cowl in between the exhaust pipes. That was worrisome, so no flying last night.
I took the cowl off today and recreated the scenario. I was able to observe fuel dripping out of the drain hole on the aft end of the FAB. I shut off the fuel pump and the dripping slowly stopped. I'm not a builder, nor a mech, just a pilot. Is this an expected occurrence?
 
Not expected behavior. The carb float is stuck / valve didn't seat. Not appropriate for flight.
 
Sounds like a bad float or crud in the needle/seat in the carb. Pull the FAB and run the pump again. If you see fuel dripping out of the carb, then thats likely it.
 
Happy Easter!

Thanks for the quick replys. Had to get back home for the Easter festivities. I'll continue tomorrow. I didn't think to check if the throttle was fully closed. It's possible I may have bumped it when getting in the airplane. If the throttle was partially open could that cause the leak?
 
Thanks for the quick replys. Had to get back home for the Easter festivities. I'll continue tomorrow. I didn't think to check if the throttle was fully closed. It's possible I may have bumped it when getting in the airplane. If the throttle was partially open could that cause the leak?

If you bumped it, you might have pushed some fuel into the carb via the accelerator pump. That fuel would have drained out through the airbox, but it shouldn't have been a large quantity.

You should check again. It should not leak. If it does, you have a problem.
 
Needle valve

I have seen this on a couple of O-320 powered RVs. In both cases, we ran the engine for a couple of minutes, shut down and tried to duplicate, with no more spill over. My theory is the engine vibration helped the needle valve seat, much like rapping on the carb of the old Farmall when the needle stuck in it...
But if it continues to reoccur, then inspection and repair is certainly in order.
 
Last edited:
That Worked

Ran the engine today for 10 minutes, did a run up, shut it down. No more leaking fuel. Thanks
 
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