I have been thinking about this all evening, since I've seen air coming through the fuel line from the filter. Does the fuel return from the back of the rail etc. go back into the filter, or straight back to the tank, and the hose is just clipped to the top of the filter?
I would go outside and look, but it's dark...
So - if it does go back in, and there's air in the rail, why would it not got back into the combustion chamber via the injectors and get burned off, and if it's not burned, would it cycle back through the filter and appear back in the fuel pipe on it's way to the LP pump?
I'm a little confused by it tonight - need more alcohol, less painting....