I am looking for ideas on a recurring engine problem that caused me 3
precautionary landings on the way from Oshkosh last weekend. The typical
setting was after an hour to hour and a half of cruise flight time the
engine would drop RPM and feel like it was ready to quit. Moving the
throttle forward made it worse and pulling it back made it better. The first
hint of a problem was on landing at Green Bay after coming up from Texas.
The engine ran at reduced power as soon as I came off the throttle to start
the decent for landing from 6500 feet. The initial thought was the problem
came from the longer idle coming down and fouling the plugs. A change of the
plugs and the engine ran on the ground for 20 minutes going in to and out of
full turbo power without a hitch. The plane was then flown for an hour to
Oshkosh and for an additional hour during the week both at low level (2500')
the return trip started out great and at 6500' and about an hour in to the
flight again the engine lost power. I tried the throttle settings and again
moving up was bad down was good. I tried both fuel pumps on and each alone,
I tried both sets of plugs alone and together with no change in the engine
response at cruise range. Another landing and calls to Lockwood for advice.
They had me inspect the filters with were just replaced prior to the trip
and clean, Next I opened the fuel pressure regulator to check for dirt,
nothing clean as the day it was built. I next check the carbs to see of they
were free floating and they were no lead build up. I then was told to report
the needle valve richer to see if that would help. Run up on the ground for
20 minutes showed no signs of problems. Next morning (Sunday) run up on the
ground looked good. Climbed up to 6500 over the airport and hung out doing
circles for about half an hour using the full range of throttle settings.
After the half hour set 5000 RPM and 30 inches and off I went. 30 minutes
latter the same old problem was back. I again made a precautionary landing
in Iowa. Having had all the fun I cold have and no new ideas the plan was
left to think about its behavior and drove home. I am taking my trailer up
to embarrass the plane in from of its new friends and pull the wings and
bring it back to Houston this weekend. Dose anyone have a thought on why
this is happening after a hour or more at cruise power? Flight up was 12
hours with no problems and it just came on very sudden. I have been burning
a combination of avgas and mogas with the trip up being all avgas. Fuel
pumps were tested the week before the flight @ 20 gallons an hour for each
pump.
Comments anyone with a 914 having similar problems?
Aircraft has 95 hours. 914 with an intercooler, AirMaster prop
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