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Fuel pressure

JOEPILOT

Member
Took the plane up tonight, on the first takeoff I heard an audible low fuel pressure warning. Everything felt fine, the pressure was fluctuating between 3.5-5.2 psi. On the next go round same warning but this time I felt a slight hiccup in the engine. The third time the same warning and the engine sputtered quick. Called it a day after that. When I was shutting down the engine I pulled the fuel pump fuse. The fuel pressure steadily dropped to almost 0 PSI. Can a failed electric pump starve fuel from the mechanical pump or is the mechanical pump my problem. Any thoughts, thanks, Joe
 
What does it do on the ground when you run it and don?t have the fuse in? No or low fuel pressure would suggest a failed engine driven pump. If the pressure comes back with the fuse back in it would seem the engine driven pump is definitely bad.

I?d check the hoses for blockage too and the carb bowls for debris just to be sure. I have experienced low pressure from vapor lock with old gas, but I also got a high fuel flow alarm. I have a switched electric pump, and turning it on eliminated the low pressure. I?ve only had vapor lock in the summer months here in Phoenix.
 
As has been mentioned, I would definitely check for debris.

I am not sure if you have the original rubber lines, or Teflon lines.

But this debris was documented and found inside a stock RV-12 Fuel system and was causing sporadic low pressures and engine issues.


Rotax%20Debris.jpg


Here is the original picture showing the debris clustered together.

Rotax%20Debris Original.jpg



So it is definitely something that warrants investigation to make sure that you aren't getting a blockage of some sort.


Steve
 
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