Hi all,
It's been a while since I have posted anything, but today I have some good news! After fighting with bubbles in my fuel lines, on my Lazair, for a few years now(I run 210cc Solo engines) I have finally solved the problem. I wished I could have known this solution when I had the Rotax 185's on my plane, as it always had bubbles in the line as well. It was a combination of my problem and another pilot with an Ercoupe aircraft that had to set his plane down, because he used Premium car gas(vapor lock problem). Since he switched back to avgas, his plane is flying well again. I did some research on avgas and it is more resistant to vapor lock, among other good qualities. So I mixed up a tank of avgas 100LL at 33-1 mix and ran the engines, no bubbles at all, at any throttle setting! The engines run smoother. I let them run at idle for awhile, then gunned it to full throttle, perfect! No hesitation at all (with Premium car gas, it would always hesitate after long idles)! So I took a short flight after a few hops to make sure I wasn't dreaming. Wow! It's a completely different airplane. So this is my first and only flight so far, but it sure looks promising! I will post again when I get more and longer flights in.
I had tried so many different set ups with the fuel lines, I even tried small "buffer" tanks near the engine to get rid of the bubbles before going into the engines. One thing that did work was an electric fuel pump pushing the gas up, but I don't have a strong enough power source to keep the battery charged for the electric pump, and I would have to have 2 pumps, one for each engine for reliability. Avgas is the answer for me and probably for anyone else that has bubbles in their fuel lines. FYI Daffy