To those who were following my engine problem during run up - I have solved
it.
The problem seemed to progress to the point of complete frustration. I
finally got the run up to be acceptable in terms of RPM drop and flew it again.
I
climbed to 10,000 feet and did a mag check on the way up -- all OK. I then
pulled the power back and the airplane began to run rough -- on both mag
together.
Changing to one mag, caused pooping noises and very bad running. That was on
both mags one at a time. The neat things was that in the long wing airplane,
this engine problem was not a big deal as the airplane outclimbs its own glide
ration at about 2 1/2 to one and I was sitting in a perfect position to return
to the field as a glider. I have done that once already on purpose.
On the ground, the Rotax expert said it sounds like the fuel pressure
regulator. The first thing to check is the hoses. I did just that and found an
obvious slit in the little air hose that attaches to the airbox. Fixing that and
rebalancing the carbs has resulted in a very smooth running engine -- even
smoother than is has ever run. I plan to put the picture of this problem on my
web
site later.
On a side note, I have designed an equation to display the fuel pressure as
it changes with manifold pressure to make an easy way to tell if the fuel
system pressure is varying correctly with manifold pressure. It wasn't
displaying
correctly and I just thought my design must have had a problem. It didn't. One
simple fix and the engine is back to normal -- purring like a kitten. I will
be changing the material those little hoses are made of as soon as I can figure
the best material to use. Keep an eye on those hoses.
Back in the air,
Dave
A227
mini U2
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