RE: OS Max 91fx Shutting off above 3/4 throttle, HELP!
It is known to have happened...check that the clunk is not too close to the tank rear wall. As the fuel flow rate increases, the clunk can (and has!) 'sucked' itself to the inner tank skin, and shut off the fuel flow. As this only happens at higher revs, and sometimes only with airborne (unloaded) revs, it can be a very frustrating problem to troubleshoot...
Evan, WB #12.