Hi
Eugene,
I
went back and reread your initial post and I feel you were correctly analyzing
the problem.
There
is a remote possibility that the vent system is at fault--however it is hard to
believe that both tank vents would be plugged at the same time.
If
you remove your fuel cap and put a rubber line into the naca vent and blow on
it--you should feel air coming out the fuel cap. If not-you probably have a
flex line kinked. If you've been flying a while without problems than it's not
likely that the vents are too small.
If
all is good here--you have to believe something is wrong with the fuel system.
That consists of three components. Engine-driven fuel pump/fuel control
(throttle valve)/fuel manifold valve.
To
have to use the electric fuel pump to keep the engine running below 10,000 feet
is indication of a problem and I would not fly the airplane until I found the
problem. You are using your emergency backup system in a normal operation.
You
don't say how many hours or years on the engine. But if these fuel system
components have over five years I would consider them due especially with the
problems you are having.
Charlie
K.
.