Yes, the Avid Flyer has this advantage...

Paul,
you might want to have a look at my previous posting for the 'fuel, wing tanks thread' where I describe problems very similar to yours.

One way or another do check all the fuel lines for debris from the tanks. If it is heavy debris and you have an up-segment of metal fuel lines before they reach the header tank like I have you might need to blow it out with an air-compressor...