Why is everyone trying so hard to limp an engine around and squeeze a diagnosis out sight unseen over the internet without just simply solving the problem by going to Wren? I have a Wren SS as well. Fortunately Wren USA was especially helpful in getting my fuel pump diagnosed as "dead" over the phone with few tests and I had a new one in a box on my doorstep and installed ASAP. Dang - you guys could almost drive to the Wren factory and just demo the issue right there and then, eh?
Please don't risk flying a sick engine and your whole jet investment, just get it fixed.