YS63FZ fuel system problem
 

Hello All,
I recently bought my first 4 stroke, A YS63FZ from an estate sale. I have no history on the engine. The engine starts easily but I am getting lots of air bubbles in the fuel line that runs from the front of the engine to the carb. The line from the tank to the engine has no bubbles. The system remains pressurized for quite a while after it is shut down.
At a friends suggestion, I replaced parts in the regulator including the o-ring, diaphram, plunger and spring. I fired it up this morning and the problem remains. Since the system is presurized, I would expect fuel to leak out, not air in. I'm not sure where the air is coming from. Any help you could offer would be greatly appreciated.
Jim

RE: YS63FZ fuel system problem
 

Bubbles in the line from the regulator to the carb are normal. Remember, the fuel is going from higher pressure to lower pressure, passing through the regulator. It is not a symptom of air getting in if the engine runs without problem, so, ignore the bubbles.


Edit for clarity.

RE: YS63FZ fuel system problem
 

Hi Jim,
Thanks for the response. I was concerned that the air in the line would cause the mixture to lean. If it's normal, I won't worry about it and go fly.
Jim Stepp