Hello:
I purchased a new O.S. 46LA about 4 months ago from Tower and have been "running" the engine for the last two months. I am about to throw in the towel and remove the engine and send back to O.S., but wanted to post here first to see if anyone has ideas.
The engine has been inconsistant and will run fine on day, but the next won't. After working out the idling issues (as it won't stay running less than 25% throttle), I thought I had it running correctly, but now it won't develop but about 10,800-11,000 RPM (using a tach) with the recommended 11x6 prop (Airscrew)....I didn't have a tach before, but at times when using OMEGA 15% fuel, it developed more power. I am now using MAGANUM 15% and it ran great for a while but now doesn't develop full power and cuts out at full and half throttle...in fact flying today it quit twice (half throttle and full throttle). The only good news is I am getting good at off field landings (20+) and fortunately I am flying a duraplane so I still have a serviceable airplane. Also, the engine would not run well using BRYON 15%: won't idle, died at half throttle, no power.

Is this engine that fuel sensitive? All the fuel I am using is brand new and yes, I have changed glow plugs (O.S. A3) numerous times and fuel lines and pressure checked the lines and fuel tank, as well as tightened all screws including the one on the back plate (BTW: when I received the engine, almost every screw was lose and I had to grind down the needle valve bracket somewhat in order to get the screw to "bite". O.S. also sent a new valve assy b/c the mounting plastic was broke).

I still notice bubbles in the fuel lines, mainly from the needle valve to the carb (have placed fuel tubing over the valve to ensure no leakage).

Any ideas on why this engine is not developing full power and the other ills?

Thanks