912 sudden power loss
in 912 / 914 Technical Questions
12 years ago
During landing, after a 1 hour uneventful flight, the engine RPM suddenly dropped from 3000 to 2000 and the engine started running extremely rough – like 1 or 2 cylinders were not producing power. Only lasted about 15-20 seconds. The throttle had not been moved for about two minutes before the power loss. I applied full throttle and the engine returned to normal – it may have been returning to normal just prior to applying full throttle.
The 100 hp engine is in a Zenith 701 and has 424 hours on it since new. No previous problems. Carbs are checked for sync once a month – never need much adjusting. Cylinder temperatures and oil and fuel pressures were normal before and after. Checked fuel for water before and after. Mags checked fine before and after. I use 91 octane auto fuel most of the time and a little 100 LL when away from home. All 8 spark plugs have nice tannish colored electrode insulators – no indication of bridging or foreign matter. No obvious loose wires or hoses on the engine. Outside temperature was 94 F, humidity 24% – density altitude was 8100’ (Colorado).
Tony
The 100 hp engine is in a Zenith 701 and has 424 hours on it since new. No previous problems. Carbs are checked for sync once a month – never need much adjusting. Cylinder temperatures and oil and fuel pressures were normal before and after. Checked fuel for water before and after. Mags checked fine before and after. I use 91 octane auto fuel most of the time and a little 100 LL when away from home. All 8 spark plugs have nice tannish colored electrode insulators – no indication of bridging or foreign matter. No obvious loose wires or hoses on the engine. Outside temperature was 94 F, humidity 24% – density altitude was 8100’ (Colorado).
Tony
