Come to think of it, you would have positive pressure if the return line has more restriction than the fuel line to the engine. Might be a good idea to over size the return line. You could even install a needle valve on the return line to adjust the pressure to some extent.

The 'Tee' method of using a Perry is normally considered to be a viable solution. The engine should run as if it had the fuel tank where the 'Tee' is.

Try it and find out for yourself...

Jim

I run the perry pump this way with the addition of the muffler pressure. This seems to give the best results...

however....

when you are running it this way, you eliminate the idea of a a sealed system ( like the cline or the stock ys). Now attitude of the plane/tank starts to play a roll again.