ORIGINAL: opjose
You mean if it the line is too flexible....
If the fuel tube is of proper length and build this is not problematic.
Usually people are replacing the provided tubes with ones that have walls that are in turn too thick.... (or too thin).
In a case such as this the tubing can pinch off as you've said.
Proper sized tubing will prohibit this as well as a little common sense.
There is just not enough space in the typical tank for a .45 size plane to allow ANY fuel line to bend to the front of the tank without kinking. While it might look ok on the bench, when you factor in all the things happening in the air, including turbulence, and the fact that the line is now subject to a vacuum, setting up a klunk that can move forward is a recipe for flameouts. As I said in my previous post, the fuel moving to the front of the tank is a red herring. If he's having problems with rolls, something else is going on.