Today while test flying my normally aspirated Lancair IV following my latest attempt to correct my engine surging problem I noted the following:

At full throttle on the runway I saw 26.2 GPH fuel flow.  As I climbed out I observed that the fuel flow was steadily dropping with no change in my WOT setting.  I climbed out to 8,500 where my fuel flow had dropped to approximately 14 GPH and the engine was running very poorly.  Not only was I getting a surge, the engine was very nearly ready to quit altogether even when I turned on the electric fuel pump.  I nosed over as I was deciding where to put down and as I decended The engine began to run much better and I noted that the fuel flow was increasing.  Even with a now smoothly running engine I felt the best plan was to get back on the ground ASAP but did not experience any engine issues on the way back in.

As a result of today's events I believe I should be looking exclusively for whatever would cause my engine's reduction of fuel flow as I increase altitude.  Much like a carbureated automobile engine would loose power when being driven from sea level to high altitude (into mountains) I believe my engine is being injected with fuel that is too rich.  I don't know if that conclusion makes any sense?

Could my problem be the unit to which my throttle and mixture controls are connected?  On my IO540 this is located on the front bottom of the engine.  Is this a rebuildable unit? If so where can I send it to be rebuilt?

Sent from my iPad
Berni Breen
Bbreen@cableone.net