OS 120 AX mid range problems
 

Hi guys...............A couple of month ago I decided to change the OS 120 4T on my Funtana 90 and installed a new OS 120 AX. I also installed a Perry pump as the fuel tank is back behind the wing tube.
Ive spent some time trying to adjust the engine settings but still i'm having all sort of troubles at mid range. The engine runs fine at idle and at full throttle with good transition between both ends but at half throttle , after a while it seems to get to rich and eventually stops.
This week end all my flights ended dead stick, 13 in total, without finding the reason of the problem.......finally decided to get back and ask for help

Thanks

Marcos

RE: OS 120 AX mid range problems
 

have you tried to back the screw out on the pump to reduce fuel pressure? sound like you may have to much fuel pressure causing it to get rich in the mid range.

randy

RE: OS 120 AX mid range problems
 

There are several versions of Perry pressure pump. Is your screw a hex head screw? If so, you should start at 2 turns out from fully in. Turning it in increases pressure; turning out decreases pressure.